Grand Teton Weather - Climbing Decision Support Page

The Grand Teton's Summer Weather 

Grand Teton Webcams

NWS Jackson Forecast
Weather Story Picture
Long Range Outlook 

Forecasts & Observations
NWS's GTNP Recreational Forecast - (summer only)
Lower Saddle Weather Station - (summer only)
NWS Lower Saddle Hourly Forecast 11,600'
NWS Lower Saddle 5-Day Forecast
Forecast for the Grand Teton's summit 13,775'
Forecast near the Lower Saddle's elevation
Remember, forecast temperatures are temperatures in the shade.
GTNP Valley Floor Weather past 10-days
Current JH Weather Observations Radar & Sat
WU's JH Forecast
MW JH Forecast
NWS JH Forecast
Weather: 307-739-3611 or 1-800-211-1448
NWS's Online Weather School
NextGen Weather Lab
Real-Time Lightning Map
14-day Precip. Totals JHMR 8179 ft / Data
The Blue Line (not green) shows recent precip
Weather Station East of Grand Teton
 14-day Temperatures JHMR 10318 ft

14-day Temperatures Valley Floor 6450 ft
JH Airport Weather Station
 14-day Wind Speeds JHMR 10318 ft
 It's Winter — JXN Roads — WY Roads
Hwy 22 Webcams. Hwy 89 Webcams
NWS State WebCam Index
Click on the forecast area to see the latest forecast. — No off-season forecast —

Lower Saddle weather graphics are
only available during the summer

Temps at the Lower Saddle - last 7 days. 

 GTPW4's recent rainfall totals at the valley floor by Moose. Rain + Low Temps = ICE.

GTGW4's recent precip (water) totals at the valley floor just east of Garnet Canyon.
Keep in mind that the mountains can get more precipitation than the valley floor.
MesoWest Stations  and Map of GTNP stations

We suspect that this weather station (GTGW4) is manually updated on a inconsistent schedule during the winter. Sometimes it will show precip when none has fallen so we are guessing that the gauge may be manually read and updated whenever they get around to it. There's another station in GTNP that has wild temperature readings. You can't trust the weatherman (or GTNP) or their data.

Jackson Hole Airport rainfall (summer only) totals last 20 days. Weather Underground JAC
MesoWest Data

Lower Saddle Wind Speeds, Gusts, and Direction (coming from)

48 hour Lower Saddle Temperature Graph
Lower Saddle Weather Station Data
A look back at the Lower Saddle's Wind Speeds and Gusts

The best forecast is the one issued on the day you are climbing; however, it's been our experience that a forecast for the Teton's during periods of moderate instability is extremely difficult for the National Weather Service (NWS) to nail down with any certainty. Storms can develop quickly right at the base of the Tetons and they can pass by just as quickly without a drop of rain or lightning. Either way, you don't want to be on the summit block if a real threat is developing. We will usually take our chances with a very small and fast moving storm cell in an otherwise mostly blue sky; however, a bolt of lightning coming out of the sky in our direction is always a possibility.

The National Weather Service out of Riverton, WY will usually forecast a temperature difference between the Lower Saddle & summit of 8°F. Their low temperature difference between the valley floor & the summit tends to be between 9°F & 13°F in their forecast. All forecast temperatures are temperatures of the air in the shade. It can feel much hotter in direct sunlight; however, the wind chill may negate any feelings of additional warmth. The wind speeds at the saddle are almost always much stronger than those in the forecast; however, the wind speeds above the saddle can die down to a more manageable level once you get past the Central Rib's Needle.
Today's National Weather Forecasts 

 Tomorrow's  Forecast

Day 3 Forecast

Current National Radar
 You must refresh the page to see new image

Short Range Forecast - 6 hours

The time shown in the above forecast graphic is in a 24hr format. 'Z' means Zulu time or UTC time + 0 hours (00Z means midnight). Mountain Standard Time (MST - winter in GTNP) is 7 hours behind UTC time. Mountain Daylight Time (MDT - summer in GTNP) is 6 hours behind UTC. A time of 00Z (midnight) would be 6pm during the summer MDT in GTNP. A time of 06Z (6am) would be midnight during the summer MDT in GTNP. 18Z (6pm) is 12 noon MDT in GTNP (11am MST). Information on weather graphics. has a nice overview of MDT & MST (Daylight Savings Time - summer, & Standard Time - winter)

Our local website feeds the National Weather Service forecast to its website during the weekends when most people would like a better forecast than that given by the NWS. Despite that drawback, the website has a great collection of weather information.
6-10 day Temp Outlook

Northern Rockies Current Radar - refresh page to refresh mage

Western U.S. Infrared - refresh page to refresh mage

Local Radar - - refresh page to refreshimage

Recent Temperatures at the valley floor.
This graph is often offline or malfunctioning.

Jackson Hole Airport Temperatures last 3 days.

Looking back at the Summer Temperatures at the Lower Saddle

Looking back at the Summer Wind Speeds at the Lower Saddle

Looking back at the precip at the valley floor in GTNP


Iowa Environmental Mesonet Historical  Data & AccuWeather Historical Data
BTW: The Historical Averages from Mesonet don't match the ones from AccuWeather.
Weather Underground's Moose, WY Forecast & Almanac


~ The Weather ~

We can have dry summers or nasty wet ones but they are usually a mix favoring more sun than rain in Jackson Hole. A typical summer provides many exceptional days for climbing. If it does rain, it's usually in the afternoon. Most climbers try to summit before noon and reach the Main Rappel to the Upper Saddle by noon but it varies with the weather.

Between June and September, summit temperatures can swing from the single digits to the 60's. Temperatures in the 20's and 30's are common when people are climbing in the early morning. During the hottest part of the summer, you will find shaded temperatures in the 40's during the morning. GTNP Weather Page.

Temperatures can change very quickly as a cold front, bad weather, or darkness moves over the area. Low temperatures can cause heavy mist to quickly freeze to rock and make it impossible to safely navigate the mountain if you are soloing. Be cognizant of the direction that temperatures are moving under wet conditions. Additionally, thick fog can make route finding difficult and hide incoming weather. The decision to turn around is always the right call if your personal safety is clouded in doubt. Safety comes first. What you don't know may kill you or your partners. Never question your decision to turn around even if others do. Mountain weather is like a game of Russian roulette. Sometimes, just waiting an hour or so will improve the weather outlook so consider taking a break if you have the time.

It is not uncommon for overnight temperatures to drop below freezing after a summer storm. Shaded ice may need a full day or longer to burn off. If you're climbing the Upper Exum, keep in mind that conditions on the west-facing Owen-Spalding route (your descent) can be far worse than anything you encountered on the sun-baked Exum ridge. Usually, thin ice can be shattered with a loose rock if you run into a problem area. Some free-soloing climbers will carry a rope for emergencies if conditions are less than ideal.

~ The Weather Forecast ~

Any forecast comes with its own uncertainty and a forecast is no substitute for common sense. A summer forecast can change dramatically in a few hours if there is any instability in the air so a forecast that's 6 hours old may be stale. Keep in mind that forecast temperatures are temperatures expected in a shaded place. It may be much hotter in direct sunlight or much colder with wind chill.

Nobody can accurately forecast the weather for a ten-mile radius around the Grand Teton during periods of moderate instability. It is possible to read the weather as it develops but it's impossible to predict the how quickly the weather will go from passing to threatening. Unless there are obvious threats on the horizon, we just head for the Grand after reading a forecast and keep tabs on the weather as we go. We have the advantage of knowing how long it will take us to move around the mountain and we feel no pressure to summit.

A forecast for showers may just mean a 5 minute storm that passes 10 miles to the south of the Grand Teton. It's important to examine a forecast carefully. Keep an eye out for rainfall totals. The NWS's hourly forecast shows expected precipitation totals. If the forecast shows a 60% chance of rain but only .01" of rain is expected, then you know that a big storm is not on the horizon. We go climbing even though the odds are favoring a short shower somewhere in the Tetons. Often, that short shower is miles away from the Grand. As we all know, a 70% chance of bad weather may never materialize while a 20% chance of bad weather does. This is especially true in the Tetons.

The word "isolated" in the NWS forecast refers to showers that are few and far between, only 10% to 20% of the forecast area will receive measurable precipitation. "Scattered" refers to the range of 30% to 50% coverage. Neither refers to intensity, amount, or time. The NWS does forecast a precipitation quantity in the hourly forecast graph; and, if you run your mouse over a graph you will see hourly percentages at the bottom of the graphics.

NWS defined terms: Rain: (Stratiform) Precipitation, in general, is relatively continuous and uniform in intensity. Sky condition usually changes little throughout the day. Showers: (Convective) Precipitation will be characterized by the suddenness in which it starts and stops as well as by rapid changes in intensity. The sky may rapidly change in appearance with peeks of blue and sun alternating with times of complete overcast.

The NWS's forecast for 11,600' near the Grand has a long history of inaccurate temperature predictions. We know this because we can look at actual data from the Lower Saddle's weather station and compare it to the forecast data. A forecast that's off by 7 degrees is not uncommon. The temperatures at the summit are often near 32°F and climbers would like to know if new ice or snow is to be expected. Those conditions are difficult to estimate if the forecast is off by 7 degrees. The good news is that free-soloing summer climbers can examine overnight temperatures at the Lower Saddle's weather station before they reach Lupine Meadows. The Lower Saddle's weather station is only available during the summer months.

Forecast wind speeds can be off by a factor of 2 at the 11,600' Lower Saddle because the NWS's wind models don't take into account the fact that the saddle represents an opening in the mountain range that the air rushes through.

Most people who look at the forecast below would reconsider their climbing plans. We examined the forecast more closely and decided it was going to be a nice day. It was.
 This was the actual forecast.
We went climbing.

The Idaho weather radar has better mapping of the western side of the Tetons. Most of our summer weather comes from the west. The localized Wyoming weather radar doesn't properly cover the Teton Range.

Local meteorologist Jim Woodmency runs It's a great source of weather information from other sources. His local forecast lacks the detail we look for in a forecast and he often just feeds the NWS forecast to his website. Besides having an interest in the weather, Woody made many notable ascents in the Tetons and was, for a time, a member of the Jenny Lake Climbing Rangers. He even survived being hit by falling rocks while on a routine mountain patrol. The Gold Face on the Lower Exum was put up by Renny Jackson and Jim Woodmencey in 1988.

"If they can make penicillin out of moldy bread, they can sure make something out of you."  Muhammad Ali

~ Thunderstorms ~

Sunny dry days are fairly common in the Tetons but so are afternoon thunderstorms. Thunderstorm usually arrive between mid-afternoon and early evening (2 p.m. to 7 p.m.). If the forecast discussion mentions monsoonal moisture, low pressure, or a cold front then that should raise a red flag. Those conditions can produce very unstable and dangerous weather. If it starts to hail in the mountains, thunderstorms are about to bust loose. Speaking of hail... it hurts. It's another good reason for using a helmet.

Storms can develop right at the edge of the Tetons. And develop quickly. Exum Mountain Guides had a group of high school students on the Grand Teton's summit ridgeline when a blast of white lightning shot through the air. They didn't see it coming and you may never see it coming.

In 2003, several climbers were struck by lightning while on the Exum Ridge and Erica Summers, a 25-year-old mother of two, was killed. In 2010, 17 people decided to climb this mountain in questionable weather. The result was the largest search & rescue operation in the park's history and the death of 21-year-old Brandon Oldenkamp. Learn from their mistakes.

There are no safe places if you are outside in a thunderstorm. Of course, you can make yourself safer. Don't group together during a storm. Ideally, stay 50-100' apart; at least 15'.  Remove all metal from your body - jewelry, biners, glasses, etc. Metal can increase the severity of burns. If you must rope up, try attaching the rope using something like an Alpine Girth-Hitch if that's even possible under the circumstances. Ropes will conduct electricity so there's a trade off between the fall-protection that the rope provides and the danger of it becoming a conductor that could easily kill you. The temptation to avoid hail and rain may drive you to caves or overhangs but they can increase your odds of getting zapped especially near the opening.

Even though most people survive a lightning strike, over 70% have permanent disabilities. The forces are similar to an IED blast and peak temperatures can reach 50,000°F. With or without lightning, climbing in the rain is a bad idea.

The summit block is a lightning rod.
The entire Lightning PDF Brochure

~ Weather Observations ~

Lower Saddle Weather Station
(summer only)
WW's Weather Page
(summer only)
Grand Teton Webcams
MW's Weather Access Map
MW's JH Observations
JH Airport Observations
Driggs, ID Airport Observations
GTNP Weather Past 10 days
Recent Timbered Island Precip
Grand Targhee and Alta Precip
TetonCounty's Weather Station
Read the Mountain Weather 
WU's Weather History

Temperatures in GTNP are, on average, cooler than in Jackson. Some of the weather stations in GTNP spit out very suspicious data when compared to the data at the nearby Airport. It may be that the location of the station is prone to trapping hot or cold temperatures that don't really represent what is going on outside of a 200' foot radius.

~ Lower Saddle Weather ~


The Lower Saddle's weather station is only operational during the summer. Besides wind speeds and the temperature, the saddle's weather station will display the wet bulb temperature and the dew point. The dew point is the temperature that the air needs to cool down to in order to achieve 100% saturation. It's the temperature at which fog, dew, or frost can form. If the wet bulb temperature is 32°F then snow is possible at that elevation. Snow levels can be 1000' lower than freezing levels.

 ~ Weather Resources ~

Mountain Thunderstorm Formation - PDF

~ See The Weather ~

NWS WY Webcam index
Grand Teton Webcams

~ Weather Contacts ~

GTNP Weather Line: 307.739.3611

National Weather Service - Riverton
Western and Central Wyoming
12744 West U.S. Hwy 26
Riverton, WY 82501

~ Typical Temperature Differences ~

There are many nights when the temperature at the Jackson Hole Airport and the temperature at the Lower Saddle are within a degree of one another. Inversions are also possible at any time of year. Temperature inversions can have a 40°F spread between the valley floor and 10,000' during the winter. During the summer, inversions are typically limited to overnight or early-morning hours.

 Inversion Temperatures: Saddle vs. Airport

As the graphic above clearly illustrates, the time of day can influence the temperature difference between two different elevations. And temperature swings at the Lower Saddle are fairly minor compared to those at the valley floor during the summer.
The Catwalk - Mid-afternoon August 9th, 2015.

A deep winter snowpack can linger on the climbers' trail throughout the summer and ice can blanket the mountain at any time of year so climbers need to be prepared for mixed conditions if they have a fixed future climbing date. Locals have the advantage of increased flexibility in their mountaineering plans whereas visitors from afar do not. In July of 1993, 6 feet of snow fell at the Lower Saddle (11,600') and it was the coldest & wettest summer on record in Jackson, WY. In 2015, it was hard to find a summer raindrop.

Shoulder-season climbers should be comfortable with mixed conditions and be prepared to travel with an ice axe and crampons. You can rent crampons and axes (and climbing shoes) at several locations around Jackson Hole including from Moosely Mountaineering inside GTNP by the Moose Entrance at the Dornan's shopping & dining area. Mountaineering rentals are fairly inexpensive at all of the rental locations.

Crampons have their own safety issues. They can catch on rock, snow, and clothing. Sharp crampons can cut your leg. They can make climbing and snow travel an awkward process for newcomers. Strong climbers who know the mountain might get by without specialized gear under poor conditions but all climbers should reconsider their climbing plans when thin ice has covered the mountain.

"I'm young; I'm handsome; I'm fast. I can't possibly be beat."  Muhammad Ali

~ Historical Weather Patterns ~
Historical Weather 1958-2012 GTNP (not Jackson)
Moose, Wyoming from 1958 to 2016
Historical Weather 1981-2010 GTNP (not Jackson)
2017 Seasonal Rainfall at the Valley Floor

The historical data above differs slightly depending upon the source. Keep in mind that the days get colder and shorter as we roll through summer. You'll have about 16 hours of daylight during the 2nd-to-last week in June when the summer solstice arrives in GTNP. You'll find more snow at the lower elevations in the month of June compared to September; however, the June days are longer and warmer. June usually gets more thunderstorms but September's storms typically bring snow and ice that sticks around. These two months are considered the shoulder season for climbing in GTNP.

Occasionally, on the hottest days, temperatures on the summit hit 60°F and overnight temperatures ping 45°F. The highest temperature at the 11,600' Lower Saddle in 2016 was 63°F on July 21st, so that would put the 13,775' summit near 55°F in the shade. Most high temperatures don't arrive until after 3:00 pm. We have seen climbers turn around in July & August simply because they didn't have gloves when the temperatures took a morning dip.

~ Historical Lower Saddle Weather Observations ~
 Lower Saddle Temperatures Summer 2015 -11,600'
 Lower Saddle Temperatures Summer 2016 - 11,600'

 Lower Saddle Temperatures Summer 2017 - 11,600'

The hottest day of the year is, on average, July 16, with a high of 79°F and a low of 48°F at the valley floor.
Lower Saddle Wind Speeds Summer 2015 - 11,600'
 Lower Saddle Wind Speeds Summer 2016 - 11,600'

  Lower Saddle Wind Speeds Summer 2017 - 11,600'

 ~ The Wind ~

Climbers have been killed & injured by wind gusts while on the Grand Teton. It's a real threat for soloing climbers on places like the Friction Pitch. Usually, however, the wind-chill temperatures cause the biggest problems for climbers.
Wind Chill Index

The wind can blow pretty hard at the Lower Saddle. Gusts reached 75 mph on August 21, 2015. The Lower Saddle's wind speed was a constant 30 mph the next morning and the temperature was 31°F at 6 am. That makes for a 15°F wind-chill temperature. If you're unprepared for a cold windy day on the Grand Teton, you're likely to turn around after a whole lot of effort & time on the approach.

Although the occurrence is not common, climbers can experience hypothermia & frostbite during the summer. Wet clothes lose much of their insulating properties and a breeze can greatly increase the rate of heat loss so hypothermia can happen in air temperatures up to 50°F. Mild hypothermia can increase the odds of an accident. The cold can be deadly. Hypothermia took the lives of several Grand Teton climbers in 1985 after a snowstorm trapped five climbers on the Exum Ridge, and hypothermia ultimately took the life of Gary Miller in 2013. Hypothermia took the toes of Aaron Gams who wrote the guidebook, Teton Rock Climbs, after he got stuck on the Middle Teton during a shoulder-season climbing trip.

“It's hard to be humble when you're as great as I am."  Muhammad Ali 

~ The Sky ~,-0.125,2/2018.04.04/19:35
The center line is solar noon
13:31 on June 21, 2018

In June, the sun sets in the northwest and burns the Owen-Spalding route clean, or tries to. Near the fall equinox, the sun sets almost directly in the west and the route burns off slowly. In the winter, it's a dark cold place with the sun setting in the southwest. The Upper Exum faces south so the sun hits it all the time. Garnet Canyon doesn't see too much sun during the winter because the sun is low in the southern sky for most of the day which means it's behind Nez Perce, etc.
Position of the Sun in the sky at 43° N

~ Grand Teton Webcams ~

Dornan's webcam inside GTNP.
Check the Time & Date. It may be an old image.

If an image is dark, the webcam may be having issues or it may be nighttime. Sometimes the live stream is working but the still image is not being captured.

View from the AAC's Grand Teton Climbers' Ranch webcam inside GTNP.
Check the Time & Date. It may be an old image.

Current Visibility in Grand Teton National Park
This graph is often offline or malfunctioning. Direct Link to visibility numbers

Enjoy Safe Climbing