The climate of the United States varies due to changes in latitude, and a range of geographic features, including mountains and deserts. Generally, on the mainland, the climate of the U.S.

West of 100°W, much of the U.S. has a cold semi-arid climate in the interior upper western states (Idaho to the Dakotas), to warm to hot desert and semi-arid climates in the southwestern U.S.

A humid subtropical climate is found along and south of a mostly east–west line from the Virginia/Maryland capes (north of the greater Norfolk, Virginia area), westward to approximately northern Oklahoma, north of the greater Oklahoma City area. Along the Atlantic seaboard, the humid subtropical climate zone extends southward into central Florida.

[failed verification] Hawaii and the U.S. territories also have tropical climates.

Higher-elevation areas of the Rocky Mountains, the Wasatch Range, Sierra Nevada, and Cascade Range are alpine. Coastal areas of Oregon and Washington have an oceanic climate.

The primary drivers of weather in the contiguous United States are the seasonal change in the solar angle, the migration north–south of the subtropical highs, and the seasonal change in the position of the polar jet stream.

In the Atlantic Ocean, the Bermuda High creates a south-southwest flow of tropical air masses over the southeastern, south-central and central United States – resulting in warm to hot temperatures, high humidity and frequent intense (but usually brief) showers and/or thunderstorms as the heat builds in the afternoon.

In the Northern Hemisphere winter, the subtropical highs retreat southward. The polar jet stream (and associated conflict zone between cold, dry air masses from Canada and warm, moist air masses from the Gulf of Mexico) drops further southward into the United States – bringing more frequent periods of stormy weather, with rain, ice and snow, and much more variable temperatures, with rapid temperature rises and falls not uncommon.

(Florida, the Gulf Coast, the Desert Southwest, and southern California) however, often have more stable weather, as the polar jet stream’s impact does not usually reach that far south.

The Gulf of Alaska is the origination area of many storms that enter the United States. Such “North Pacific lows” enter the U.S.

Across the central states from late fall to spring, “Panhandle hook” storms move from the central Rockies into the Oklahoma/Texas panhandle areas, then northeast toward the Great Lakes.

Across the northern states in winter usually from Montana eastward, “Alberta clipper” storms track east and bring light to moderate snowfalls from Montana and the Dakotas across the upper Midwest and Great Lakes states to New England, and often, windy and severe Arctic outbreaks behind them.

In the cold season (generally November to March), most precipitation occurs in conjunction with organized low-pressure systems and associated fronts. In the summer, storms are much more localized, with short-duration thunderstorms common in many areas east of 100°W and south of 40°N.

In the warm season, storm systems affecting a large area are less frequent, and weather conditions are more solar {sun} controlled, with the greatest chance for thunderstorm and severe weather activity during peak heating hours, mostly between 3 PM and 9 PM local time.

From late summer into fall (mostly August to October), tropical cyclones (hurricanes, tropical storms and tropical depressions) sometimes approach or cross the Gulf and Atlantic states, bringing high winds, heavy rainfall, and storm surges (often topped with battering waves) to Gulf and Atlantic lowlands and coastal areas.

The Southwest has a hot desert climate, at lower elevations. Cities like Phoenix, Las Vegas, Yuma, and Palm Springs have average highs over 100 °F (38 °C) during the summer months and lows in the 70s or even 80s.

In Phoenix, Las Vegas and similar Southwestern desert areas, on average June is the driest month, after Pacific-originating winter storms have concluded and before the Southwestern summer “monsoon” begins. The Southwest and the Great Basin are affected by said monsoon from the Gulf of California from July–September.

Further eastward in the desert Southwest (Tucson, Arizona eastward toward El Paso, Texas), winter-season precipitation decreases, while the summer monsoon increasingly provides a summer precipitation maximum. For example, El Paso and Albuquerque, New Mexico have a pronounced July to September precipitation maximum.

Forest fires across the Western United States (especially the southwest) occur many years, and can be severe to extreme in especially hot, dry summer seasons.

Summer high temperatures often reach the 90s, but low temperatures drop into the low 60s and even 50s. As in other temperate desert climates, the dry air results in large differences (sometimes over 40 degrees) between daytime high and nighttime low temperatures.

The coast of California has a Mediterranean climate. Daily high temperatures range from 70 to 80 °F (21 to 27 °C) in the summer to 50 to 65 °F (10 to 16 °C) in winter, with low temperatures from the 60 °F (16 °C)s in summer to the mid 40s F in winter.[citation needed] Like most Mediterranean climates, much of coastal California has a wet winter and dry summer.

As such, the warmest summer weather is delayed until August, even September in many areas of the California coast. on average, September is the warmest month in San Francisco.

In California’s inland river valleys (Bakersfield, Sacramento areas), the wet-winter, dry-summer pattern remains, but winters are cooler and more prone to occasional frost or freeze, while summers are much hotter, with blazing sunshine and daytime high temperatures not uncommonly in the 90s to over 100 °F (38 °C).

The Gulf and South Atlantic states have a humid subtropical climate with mostly mild winters and hot, humid summers. Most of the Florida peninsula including Tampa and Jacksonville, along with other coastal cities like Houston, New Orleans, Savannah, Charleston and Wilmington all have average summer highs from near 90 to the lower 90s F, and.

Layering is your best friend in 60 degree weather. Build on lighter layers, like a cotton t-shirt.

Jeans and chinos are a good bet on bottom, and you have a wide variety of shoe options, from loafers to boots. It’s not warm.

And it’s not quite cold. It’s 60 degrees outside and you’re wondering what to wear.

At that temp, the weather can turn either way, so you want to prepare for when the sun pops out and you want a little more color on your arms, but you don’t want to be caught off-guard if a chilly wind comes through (even better if you have a jacket on hand for the lady).

Skip Ahead. Layering is always a good idea in 60 degree weather.

But when the sun comes out, you can start sweating up a storm.

But another great option is a button-up shirt that looks nice with the sleeves rolled. If it warms up, just cuff your shirt and let those wrists breath.

These are four of my favorite outfits for 60 degree weather: I wear this ensemble more than anything else when the temperature dips down and leaves start falling.

Crafted from a loose weave premium Italian oxford 2% stretch cloth, thiis one of the softest Oxfords we’ve got our Adult Man hands on in recent years. It’s hem and slightly relaxed color makes it versatile enough to dress up or down with ease.

Go with the season: fall lends itself well to the warm end of the color-spectrum, with burgundy, oranges, and yellows being the obvious contenders. We thought summer was never going to end.

You don’t want to miss it. You might not like the way warmer colors pair with your skin—no worries, brown and black are also excellent choices in the cold months.

But this combo isn’t only for fall and winter—early spring can be just as fickle, and a good quality Oxford shirt adds more warmth than you’d think. The outfit above features a t-shirt and Oxford from Frank And Oak (read our review of their Style Plan here), and some raw denim jeans from Mott + Bow.

Mott & Bow are our go-to for slim fit jeans in the sub $150 category. The sturdy 13oz denim of the Oliver, paired with its slim profile, makes for a clean and comfortable design that feels like it should be much more expensive than it really is.

I like to keep the top buttons undone and the sleeves rolled to keep the look relaxed.

The key to making this outfit look clean is getting the right fit on both pieces.

This helps reduce the amount of fabric, which means less billowing. The Oxford is a more casual choice than a dress shirt, but you can still throw a blazer on top: wool is a good look for fall/winter, while cotton and linen are best reserved for spring/summer.

Name me a more versatile pant. I shall wait.

They’re from Collars & Co, so they’re well made and hold up well—but I also like that they use 4-way stretch technology, it makes them noticeably more comfortable than non-stretch chinos. Do you run a little cold.

A henley and bomber is a suitable outfit for a casual night on the town as you’ll stay warm for hours after the sun sets.

I’m wearing an Everlane Waffle-Knit Henley and the buttons add a more intrigue than a long sleeve shirt would otherwise.

It makes for an excellent layer for fall and winter. The jacket is the Skyline Bomber from Frank And Oak, and it’s a powerhouse.

The quilted pattern does well in the cool months: extra texture is always welcome in fall and winter. And the more minimalist side is a go-to for chilly spring days.

A good chore jacket is a wonderful thing. These thick-gauge, heavy-cotton shirts do the trick when the weather isn’t leaning one way or another.

Think of the chore jacket (a.k.a shacket) as the Oxford’s heavy, rugged cousin. So long as you keep the chore jacket untucked, you can style it all the same ways you would an Oxford.

Try it open over a t-shirt like you see above, or buttoned up with a pair of jeans.

The Ace Marks Troy Chelsea Boot is made with premium Italian calf-skin leather and a Blake stitched construction. It’s lightweight, creamy-smooth, and has a stunning profile.

The Commuter Pants take chinos to a new level. We haven’t found another pair of technical fabric chinos that does so well looking like standard cotton slacks but still retaining the extra comfort and mobility of other tech-forward pants.

But since a lot of guys ditch their boots for sneakers and flip-flops in the height of summer, 60 degree days are the perfect opportunity to dust them off. A Chelsea boot is extremely versatile and works in every season.

Blake stitched for a sleek profile, the tobacco color of these suede Chelseas pairs incredibly with denim and adds texture to your outfit. The best part.

Want more of a rugged look. Service boots are a must in every guy’s wardrobe in my opinion.

They’re typically made with thick leather, which isn’t the greatest for breathability. Plus, they’re often a lot heavier because they’re built for durability.

A pair of Goodyear welted boots like these Thursday Captains will last a decade if properly cared for.

The leather is similar to Horween’s Chromexcel, so it has a subtle shine and plenty of rugged durability. When (if.

A post shared by The Sartorial Finn || Johan W. (@sartorial_finn) on Oct 22, 2020 at 5:33am PDT.

But when the “embers” come along (September, October, November) loafers can take on a whole new personality.

Combine that with a pair of classic socks for a classy, refined look. Match the socks to your trousers—not to your loafers.

We’ve found MYRQVIST to consistently offer great value for money with their Portuguese handcrafted dress shoes and the Stenhammar loafer is no exception. They’ll effortlessly elevate your business casual or dinner date outfit.

What if you’re just heading outside for a few errands and don’t want to don a blazer and your most baller loafers. That makes sense to me.

Grab a pair of sneaks—they’re perfect for when you want to throw something on and head out the door.

If you’re a sneaker-head, you probably feel differently than I do, but I err toward a more timeless look.

A few of my favorite sneaker brands are Oliver Cabell and GREATS: they each make top-quality minimalist sneakers a la Common Projects but at a much more reasonable price.

Made in Italy from full grain calfskin Italian leather, it boasts a handsome low-profile silhouette and punches well above its weight for its price point. A post shared by One Dapper Street (@marcelfloruss) on Sep 26, 2020 at 10:33am PDT.

Bombers and hoodies pair well together and have a relaxed, street-wear vibe. Choose a monochromatic pairing like the photo above, or try a contrast like black and white.

What used to be military gear is now a casual essential. Check out the five best bomber jackets for men, from slimmed down tech versions to the WWII classic.

A post shared by ALEX COSTA (@alexcosta) on Oct 20, 2020 at 7:52pm PDT. This outfit is quick and easy to throw together—not to mention comfortable.

Figuring out what to wear on your run is often a bit more difficult than we expect. Not only do we have to account for the temperature, but we have to take in account the various elements of the weather and season.

Raining. Snowing.

All of these factors influence the running gear we choose. Not to mention how comfortable you feel each day logging various miles.

Learn how to choose the right running gear here. However, having an idea of the number of layers, type of clothes, helpful accessories and essential gear that will be needed in every kind of weather can really help speed up the process.

We all know what it feels like to step outside and find ourselves unprepared for the weather. Finding yourself facing a freezing headwind, surprised by a sudden downpour, or sweating buckets in 80% humidity is usually all it takes to make us re-evaluate the way we dress for a run.

Here is a breakdown of what to wear running in every type of weather. This handy temperature chart can help you determine what type of layering will need to take place, the kind of running gear you’ll want to wear, and any helpful accessories you may wish to take with you.

In addition, wearing the right running clothes will help keep you comfortable when the weather is less than ideal. Regardless of how intense the weather may appear to be, it is possible to comfortably run outside with the right gear (with the exception of dangerously cold or hot temperatures).

In general, runners should dress as if the temperature were 10-20 degrees warmer than the “real feel” temp with the wind chill. However, if you base your running outfit on what you wear outside when you are just running errands or sitting in the backyard, you’ll likely find yourself quite a bit too warm on the run.

However, when the temperature is chilly, layering is the key to staying warm and comfortable. In addition to just dressing to stay warm, many of us have to use quite a few accessories to keep us safe on snow and ice.

When the temperature is below 0, it’s probably best to stay inside and hit the treadmill. However, if you are bound and determined to head outside for a run, wearing the right running gear for cold weather is key to your comfort and safety.

A running jacket is best for your top layer to keep you safe from the wind and cold air. Thick running socks, a hat, neck scarf and mittens or gloves of some sort will be a necessity.

In temperatures between 0 and 20 degrees, you’ll need to wear running clothes that keep your body warm and safe from the cold. You’ll want at least two top layers plus a jacket or windbreaker.

While these temperatures are certainly still cold, they can feel like a bit of a heat wave for those of us enduring bitterly cold winters. When the temperature is between 20 and 40 degrees, you’ll want two long sleeve top layers, plus full-length tights, gloves and a headband.

Spring running season is often a welcomed change for many runners after enduring the brutal winds and chilly temperatures of winter – that is, until we find ourselves drenched from cold rain. Dressing for running in the spring often requires having a variety of different options on hand.

When the temperature is in the 40s, you’ll still want a long sleeve shirt and either full length tights or capris, depending on your personal preference. If the weather is especially windy, it might be helpful to bring along a lightweight windbreaker to protect you from the wind.

If the temperature is in the 50s, you’re in luck: this is ideal running weather for most of us. Learning what to wear for 50 degree temperatures is the easiest of all because it often requires very little extra gear.

If it’s really windy, those lightweight windbreakers can still be especially handy to keep you warm in a headwind. Some runners still like to take along some light running gloves for the beginning of their runs as well.

Temperatures in the 60s are another favorite for most runners. You’ll want to wear a short sleeve shirt plus either capris or shorts now.

Things can start to feel a bit toasty now, so it might be helpful to bring along a hat or visor to help keep the sun off your face and avoid heating up too quickly. Summer running season can be deceiving.

However, dressing for summer runs usually requires the least amount of effort. Choosing what to wear for summer runs often involves a very simple outfit, but bringing along some extra gear will help keep things comfortable.

In this type of weather, you’ll want to wear either a tank top or short sleeve shirt with shorts. Try some lightweight socks to avoid excessive sweating that can lead to blisters.

A handheld water bottle is a simple addition to your ensemble for longer runs to help avoid dehydration or overheating. When the temperature is above 90, you might consider taking your run indoors on the treadmill.

A tank top and shorts are all you’ll want to wear when the temperature is this high. Be sure to wear a visor to keep the sun off your face and avoid any hats that can soak up the sun.

Fall running season is a favorite for most runners, and for good reason. The temperatures are nearly perfect – things are cooling down after a hot summer running season, and the humidity has disappeared.

When deciding what to wear for fall running, you’ll want to follow similar guidelines to spring temperatures. Things might feel a bit cooler than usual if you’re coming off a season of hot weather running, so be sure to always have a light pair of gloves on hand for the beginning of your runs.

Selecting the best running gear for the weather will help make nearly any temperature feel comfortable. Dressing appropriately for the season helps keep you safe and ensure you have the best opportunity to conquer your run.

The fall 2022 warm weather hits just keep on coming. Upper air and surface forecast maps push yet another unseasonably warm air mass into Minnesota starting this weekend and peaking later next week.

First, we pine for the few light showers that will move across Minnesota overnight. Unfortunately, rainfall will be light and not a significant factor in easing our extreme drought.

Sunshine returns to Minnesota from west to east on Friday. Highs will be in the 60s for southern Minnesota Friday through the weekend.

MPR News is supported by Members. Gifts from individuals power everything you find here.

Halloween looks as good as it gets this year for trick-or-treaters in Minnesota. Sunshine, light winds and mild temperatures will make for one of the best Halloweens on record.

Here’s the full rundown on Minnesota’s Halloween climate history from the Minnesota State Climatology Office. Halloween is typically a time of crunchy leaves on the ground, a bit of chill in the air, and lots of candy.

It is more common for the daily high on Halloween to be in the 60s than in the 30s. 70s tend to be rare, with only eight Halloween high temperatures being 70 degrees or above or about one in eighteen years.

The coldest Halloween maximum temperature was a bone-chilling 26 degrees back in 1873. The last twenty-five years have had some balmy Halloween afternoons, like the 71-degree F high in 2000.

The area has not seen a Halloween washout, with measurable precipitation during the evening, since 1997. Measurable precipitation has occurred on Halloween only 26% of the time in the Twin Cities, or 38 times out of 145 years.

In 1991.85 inches of precipitation fell, which was snow. In spite of the 1991 Halloween Blizzard, measurable snow on Halloween is about as rare as getting a full-sized candy bar in your trick-or-treat bag.

0.2 in 1885. 1.4 in 1932.

0.5 in 1995. and of course 8.2 inches, with the opening round of the Halloween Blizzard in 1991.

Next week’s weather maps look unseasonably warm. Highs in the mid to upper 60s look very likely for the Twin Cities and southern Minnesota next week.

And 70s look possible late next week. The National Oceanic and Atmospheric Administration’s Global Forecast System model is cranking out highs well into the 70s by late next week.

Stay tuned.

The weather in Glacier National Park ranges from summer high’s in the 90s to the negative digits in the winter. Even in the ideal summer weather window, temperatures and conditions vary widely and change rapidly.

So how can you be prepared for the weather on your next trip to Glacier.

You’ll also get recommendations to help you enjoy Glacier, rain, shine or in the snow. As Alfred Wainwright once said, “There’s no such thing as bad weather, only unsuitable clothing.”.

Tucked in the Northwestern corner of Montana where the Rockies meet the plains, Glacier is subject to rapidly changing conditions in different parts of the park. Each season in Glacier Park brings about its own unique weather patterns and considerations.

The temperature in Glacier is obviously one of the most important factors. If you’re visiting anytime besides July or August you should be prepared for the possibility of freezing temperatures at night or at higher elevations.

Don’t just look at the weather forecast and take one temperature as a given truth. Consider your elevation and factor in a significant drop in temps as you drive or climb from the level of Lake Mcdonald up to Logan Pass and beyond.

Source: NOAA for West Glacier, Montana. Wind is the next critical element to think about.

If you plan to drive up Going-To-The-Sun Road to do a hike to Hidden Lake Overlook or the Highline Trail, ensure you’ve got adequate protection from wind by bringing a rain jacket and either soft-shell or rain pants.

With that said, ALWAYS bring a rain jacket with you in Glacier. What starts as a sunny day can quickly change to an afternoon thunderstorm.

Of course, if you plan to come in the spring, be prepared for rain and be pleasantly surprised if you get sun. May and June are the two rainiest months of the year in Glacier National Park.

This is an incredible sight, but we can’t urge you enough to keep a safe distance from the river’s edge. Drowning in rivers is the number one cause of death in Glacier National Park, so respect this force of nature and keep you and your family at a safe distance as you look at the beautiful waterfalls and rapids.

Source: NOAA for West Glacier Montana. Local Tip: April can be a sneaky month for pleasantly nice conditions and zero crowds.

Summer fires should be an additional consideration as you plan your trip. If there is a low snow year and a hot, dry July you can expect that August will likely bring fires and smoke from the surrounding area.

Fires in the park can close off large sections of it, but this is relatively uncommon. More often, the smoke from fires in other parts of Montana and Canada can come in so thick as to obscure the magnificent views of the surroundings.

Spring is a wonderful time to discover lower-elevation hikes or raft whitewater rapids on the Middle Fork of the Flathead River. May through June brings the most precipitation of any season in Glacier with highly variable weather conditions.

Typical high temps are in the mid-50’s and mid-60’s in April and May respectively. Lows are mostly in the 30’s.

The snowpack will be the most important weather factor for your spring visit to Glacier. From early May through late June, the snow lines will rise and the road crews will clear Going-To-The-Sun Road a bit closer to Logan Pass each day.

Come prepared for spring weather and you can beat the crowds and find much cheaper lodging than in the summer months.

Check the weather before you get into Glacier as there is no service throughout most of the Park. Bring bug spray as the mosquitos are at their “prime” in late May and June.

Mid-June through Labor Day is absolutely lovely in Montana. As locals, we endure the cold, dark days of November and March so we can enjoy the spectacular weather and beauty of Montana in the summer.

Recent years have seen more days in the 90’s so it is imperative that you stay hydrated and bring plenty of sun protection.

While July and August have the lowest precipitation all year, sudden storms will still roll in and can drop a lot of rain in a short amount of time through “cloud bursts”. These systems can also cause temperatures to plunge so you don’t want to be caught without your warm layers.

A typical day will be mostly sunny with a few clouds throughout. On average, roughly 75% of the time we get sunny days in Glacier during the summer.

Cool off on a hot day with whitewater rafting and some famous huckleberry ice-cream. Or take a hike to one of our favorite lakes for swimming in Glacier National Park (Link).

ALWAYS have a rain shell or windbreaker. If you’ll be away from your car for more than a couple hours, add a hat and gloves when hiking in Montana.

Fall is perhaps my favorite time in Glacier. All of the roads and trails are still open, the colors are changing and the crowds have dispersed.

Expect high 60’s in September and mid 50’s in October.

The mornings are crisp and the nights are cold, dropping into the high 30’s. Sunshine still abounds, but you’ll likely have more fun hiking and biking than playing on lakes and rivers as the water temps drop considerably in September too.

Later in September, you will encounter more rainy days. High in the mountaintops a few dustings of snow appear, but not enough to limit travel.

As temperatures cool in early October, the colors descend the mountains into the valleys below. After Labor Day, you can find much cheaper lodging and deals on activities around Glacier.

By the end of September nearly all amenities are closed up for the year.

Throw in an extra pair of wool socks and you’ll thank us later. Bugs are not an issue in the fall, but do carry your bear spray anytime you are hitting the trails.

Glacier is a winter wonderland from December through March. Most of the park has limited access with the primary point of entry through West Glacier.

By March it warms considerably into the mid 40’s and the snow begins to melt.

This can make for lovely snowshoeing (link) and cross-country skiing in the area. Just park near the Lake McDonald lodge and head up the road from there.

For the adventurous, the south side of Glacier can offer spectacular views and fantastic cross-country skiing. Be prepared for colder temperatures and higher winds as you climb to 5,213 feet at Marias Pass.

We suggest taking a local guide if this area is new for you.

Where lots of layers with down or fleece covered by waterproof shells. Bring hand-warmers and thick wool socks.

Being stuck in the winter in Glacier is no joke.

January is the coldest month in Glacier with average highs of 28 degrees. It also brings the most snow and precipitation of any winter month.

Temperature. Because of its elevation, Wyoming has a relatively cool climate ranks 41st in the US with an annual average of 45.6°F (Figure 3.1).

The warmest parts of the state are the lower portions of the Bighorn Basin, the lower elevations of the central and northeast, and along the eastern border. The highest recorded temperature is 116°F on July 12, 1900 at Bitter Creek in Sweetwater County.

For most of the state, the mean maximum temperatures in July range between 85°F and 95°F. With increasing elevation, average values drop rapidly (5.5°F per 1,000 feet).

Summer nights are almost invariably cool even though daytime readings may be quite high at times. For most places away from the mountains the mean minimum temperature in July ranges from 50°F to 60°F.

In the wintertime, it is characteristic to have rapid and frequent changes between mild and cold spells. Usually there are up to 10 cold waves that hit the state but frequently less than half that number for any one location in Wyoming.

Sometimes only the northeast part of the state is affected by the cold air as it slides eastward over the plains. Many of the cold waves are not accompanied by enough snow to cause severe conditions.

In the western valleys mean values go down to about -5°F. The record low for the state was originally -66°F observed February 9, 1933 in Yellowstone Park.

-63F at Moran 5WNW is the next likely contender.

By definition, in this study an extreme temperature that equals or exceeds two standard deviations based on the 55 winter average daily maximum and minimum temperatures was used. Linear trend lines show that winter extreme cold days have been diminishing from just over 4.2 days per winter to 3.2 days while extreme warm days in winter have increased from just over one day every two winters to about 1.4 days every two winters.

While the average number of extreme maxima seasonal events varied from 2.6 days or less (i.e., 1980-1, 1994-5), extreme minima events were as high as nearly 13 days on average in 1978-9 to nearly no events in 1982-3, 1966-7, and 1999-2000.

This exception can be explained in part since during the first winter of the study, there were 21 days of extreme cold. If there were about half that number, the trend would be -3.4 days while if there were no extreme cold days, the trend would be only -2.3 days.

The maximum number of days of extreme temperatures during the 55 winter seasons is listed by season if two or fewer seasons had the same maximum number of days.

Figure 3.0. Wyoming Winter Extremes (temperatures >=ABS(2sd)).

Table 3.1. Wyoming winter season average days when daily max and min temps >=ABS(2sd).

Table 3.2. Wyoming winter cold & warm waves (>ABS(2sd)).

Chinooks, warm downslope winds, are common along the eastern slopes.

Protective mountain ranges prevent the wind from stirring the air, and the colder, heavier air settles into the valleys often resulting in readings well below 0°F. It is common to have temperatures in the valleys considerably lower than on the nearby mountainside.

Mean January temperatures in the Bighorn Basin show the variation between the lower and upper parts of the valley. At Worland and Basin in the lower portion of the Bighorn Basin, not far from the 4,000-foot level, the January mean minimum temperature is 0°F, while Cody, close to 5,000 feet on the west side of the valley, has a January mean minimum of 11°F.

however, winters are usually long and cold.

Figure 3.1. Annual average temperature in Wyoming (PRISM).

Many a bet has been waged during coffee breaks and many are surprised by the answers. For example, Wyoming has experienced a temperature span of over 180°F between its all time highest and lowest readings (Table 3.A.

Figure 3.2. Average number of days each year with temperatures above 90°F in Wyoming (PRISM, 1961-90).

Figure 3.3. Average number of days each year with temperatures of 32° F or lower in Wyoming (PRISM, 1961-90).

In Figure 3.2 and Figure 3.3, the average number of days with temperatures warmer than or equal to 90°F and equal to or cooler than 32°F are shown. Excessively hot days are rare at higher elevations but are common in the Bighorn Basin and eastern plains (>40 days).

Table 3.A. Wyoming temperature records (° F).

12 Jul 1900. Bitter Creek.

-66 / -63. 9 Feb 1933.

(under Review) -63F at Moran 5WNW is the next lowest. Highest Average Annual Temp.

Lingle 2 S. Lowest Average Annual Temp.

Darwin Ranch. Consecutive Days Max >= 90.

Jul-Aug 1964. Basin.

277 days. Oct 67-Jul 68.

1981. Recluse 14NNW*.

1875. Fort Sanders.

1995. Weston*.

1933. Riverside RS (Under Review) / Moran 5WNW.

1907. Pine Bluffs.

1906. Snake River YNP.

1948. Basin.

1920. Lake Yellowstone.

1934. Sundance*.

1912. Foxpark.

1988. Whalen Dam.

1978. Burgess Junction.

1900. Bitter Creek*.

1911. Lolabana Ranch.

1983. Basin.

1910. Fountain Hotel YNP.

1978. Colony.

1983. Big Piney.

1947. Hampshire*.

1917. Soda Butte YNP.

1914. Wheatland.

1976. Darwin Ranch.

1939. Sheridan*.

1924. Riverside RS.

Heat Stress Index is defined as the combination of high temperature and humidity that humans can physically tolerate. In the US, extreme heat may have a greater impact on human health (Kalkstein and Davis, 1989), especially among the elderly (Changnon et al., 1996), than any other type of severe weather.

Ignoring wind effects, one can estimate apparent temperature as:.

Figure 3.4. NOAA’s Heat Index table.

The apparent temperature of “how hot it feels” should not be confused with the Heat Index 17 (Figure 3.4) used by NOAA’s National Weather Service. Because the latter index is not defined for temperature below 80°F (27°C) and relative humidity below 40 percent, it is not suitable for compilation of a climatology.

Therefore employment of the Steadman (1984) apparent temperature is used. Table 3.C.

For each station, three-hourly July and August data for 1961-1990 were used to determine the 85th percentile values of daily average, daily minimum, and daily maximum ambient temperature and apparent temperature in °F. The 85th percentile values have been shown to be closely correlated with weather-related mortality statistics (Kalkstein and Davis, 1989).

In several instances, the apparent temperature is lower than the actual temperature because of very low relative humidity.

HEAT STRESS INDEX (threshold). Apparent T thresholds (° F).

avg, max, min. avg, max, min.

71.0, 83.2, 59.6. 72.4, 86.6, 59.6.