The Grand Teton National Park climate varies quite a bit with elevations ranging from just over 6,000 feet to 13,770 feet at the top of the Grand Teton. In general, the park experiences cold and snowy winters, warm and dry summers, and cool and unsettled fall and spring seasons.
Generally speaking, early July through early September features the nicest stretch of summer weather with warmer temperatures and less precipitation than any other time of year. However, afternoon thunderstorms are common during the summer and in some years smoke from wildfires can periodically be an issue in late summer.
During the spring and fall, weather is more variable with a mix of nice/sunny days and stretches of cool, wet, and even snowy weather.
In the Grand Teton (Jackson Hole) Valley between 6,000 and 7,000 feet, average high temperatures range from the low 80s in the summer to mid 20s in the winter, and low temperatures range from the low 40s in the summer to around zero in the winter.
Summer and fall temperatures in particular vary widely between warm days and chilly nights, which necessitate always having extra layers on hand.
During the spring, summer, and fall, daytime temperatures generally decrease by about 5.5ºF f per 1,000 feet of elevation gain. If you’re hiking some of the higher elevation trails around 10,000 feet, that means you can expect temperatures to be roughly 20 degrees colder compared to in the valley.
Nighttime and early morning temperatures do not follow this same rule of thumb. During periods of clear/dry weather, a phenomenon known as a “temperature inversion” typically occurs, when colder air sinks into the valleys. As a result, the coldest low temperatures often happen in the Jackson Hole Valley as opposed to the higher elevations.
Below are month-by-month average temperature charts for Moose Junction and Jackson Lake, both located in the valley. Temperatures generally cool slightly as you head farther north in the park toward Jackson Lake.
The daily average temperatures for each month are provided, but I also provide the average “warmest” high temperature and “coldest” low temperature during each month to give an idea of the range of variability you can expect in a given month.
For example, on any given day in May the average high and low temperatures in Moose are 62 and 32. However, on average the warmest temperature of the entire month in Moose is around 77 degrees, and on average the coldest temperature of entire month is 19 degrees.
Average Temperatures – Moose (6,466 ft.)
Average Temperatures – Jackson Lake (6,777 ft.)
Precipitation and Rain
Precipitation varies significantly over the course of the year with areas above 9,000 feet average over 50 inches of precipitation annually, while the Jackson Hole Valley receives 23-25 inches of precipitation annually. Precipitation drops off even further south with the Town of Jackson averaging about 17 inches annually.
The mountains are responsible for these variations, due to moisture being forced to rise as storm systems encounter the western slopes of the Tetons. By the time systems move across the mountain range and reach the valley east of the Tetons, they have already lost quite a bit of moisture, thus precipitation is lighter.
Spring and summer “pop-up” showers and thunderstorms distribute precipitation more evenly between the mountains at the valley due to the more random nature of these showers, compared to more organized systems in the fall, winter, and early spring.
The rainiest months in Grand Teton National Park during the warm season (May to October) are May, June, and October, and the driest months during the warm season are July, August, and September.
Grand Teton National Park experiences very snowy winters with average annual snowfall of 150-175 inches in the valley between 6,000 and 7,000 feet and over 500 inches in the Teton Mountains above 9,000 feet.
Snowfall is heaviest from December through February on average, but snow can fall as late as June and as early as September in the valley. In the mountains, it can snow at any time of year above 9,000 feet though it is not common in July and August.
Snowpack reaches its deepest heights in March in the valley and in April in the mountains before gradually decreasing through the spring. Hiking trails that cover the highest passes above 10,000 feet often see snow patches lingering well into July.
The first snows of the new season in the mountains typically happen in September, but consistent snow that hangs around doesn’t arrive until October (and in the valley, November).
Below are the monthly precipitation and snow depth comparisons at Jackson Lake (elevation 6,877 feet) and Grand Targhee (elevation 9,260 feet), the latter of which is located on the western slopes of the Tetons but provides the closest approximation to conditions across the higher elevations in GTNP.
“Snow depth” is the amount of settled snow on the ground, and is not the same as “snowfall” which is the amount that falls from the sky but compacts and settles over time.
Average Monthly Precipitation and Snow Depth – Jackson Lake (6,777 ft.)
Average Monthly Precipitation and Snow Depth – Teton Mountains (9,260 ft.)
May is the rainiest month of the year in Grand Teton National Park and temperatures are a lot cooler compared to most parts of the U.S. at that time of year. Rain showers are common at this time of year, but usually they are intermittent with breaks in between, while all-day rainouts are less common. Thunderstorms occasionally happen in May as well.
Snow can also fall in May, even down to the valley floor, though accumulations at the lower elevations are typically light and melt quickly.
June is a transition month between spring and summer with rain showers becoming less frequent compared to May and warm/sunny days becoming more common. However, thunderstorms are more common in June compared to May.
There are usually a couple of late season cool/wet systems that bring more widespread rain showers and even late season snow to the mountains. During cold snaps, snow can even fall in the valley in June but accumulations (if they happen) are light and short-lived.
June also has many fine days as well with warm and sunny weather.
July and August
July and August are by far the two warmest and driest months of the year in Grand Teton National Park. This short “dry” season results in abundant sunshine with warm days and cool nights.
The southern portion of the valley usually reaches 90 degrees on a couple of days per summer. By late August as the days get shorter, nights become noticeably cooler with lows in the 30s becoming common.
Afternoon thunderstorms are common at this time of year but typically rainfall is short-lived from these storms with only occasional stretches of weather featuring stronger/wetter thunderstorms.
Thunderstorms are typically not as strong or frequent compared to areas farther south in Colorado or even in other parts of Wyoming, yet lightning is still a significant concern for hikers and climbers spending time in the exposed higher terrain of the Tetons.
High elevation snow (above 9,000 feet) during mid-summer is not common, but it has happened on a few occasions over the past several years – just a reminder that anything is possible in the high country.
As wonderful as the weather is at this time of year, unfortunately there are some years in which wildfire smoke becomes an issue periodically. This can occur either from local fires or from fires in other areas upwind of the Tetons such as California or Idaho.
Dry season often lasts well into September, but the first cool/wet systems of the season usually arrive in between stretches of dry and sunny weather. Temperatures also cool off considerably over the course of the month with low temperatures routinely falling below freezing on clear nights.
The mountains will see their first snowfalls of the season in September, and occasionally heavy snow can fall, but snow from these early season storms typically melts off in the days to follow.
Snowfall is more common during the second half of the month, but in some years the first snow happens early in the month. Low elevation snow is uncommon but occasionally happens late in the month.
Thunderstorms are less common in September compared to June through August, but they still happen on occasion, especially early in the month or at the leading edge of organized storm systems any time of the month.
October is a transition season in Grand Teton National Park. Prolonged warm/sunny stretches remain possible, especially early in the month, but cloudy/wet weather starts to become more common as the month progresses and winter begins to set in across the higher elevations.
Overall, October is wetter than June through September with periods of rain and snow becoming more frequent, and temperatures are much colder as well.
The valley sees its first accumulating snowfalls of the season in October, though it typically doesn’t stick around for long. Across the higher elevations, snow becomes more common and may not melt off until the following spring/summer.
Winter (November – April) in Grand Teton National Park
Winter begins to set in across elevations during November. December and January are the two coldest and snowiest months on average, but February often sees its fair share of heavy snow and/or bitterly cold temperatures as well.
Temperatures are typically less extreme during snowfall events, while clear/dry spells in between storms in the mid-winter months support much colder temperatures with lows often falling well below zero.
Temperatures start to warm up noticeably in March as the days get longer and the sun gets stronger, though snowpack remains deep. During April, the snowpack begins to melt off in the valley while the melt is slower/more gradual this early in the spring in the mountains.
Despite the overall warming trend, new snowfalls remain common in March and even April as well. Snowpack can also linger across parts of the valley well into May.