Grand Teton Weather - Climbing Decision Support Page

The Grand Teton's Summer Weather 



Grand Teton Webcams


http://www.weather.gov/riw/drought_5

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
↓Mountain-Forecast.com↓
Forecast for the Grand Teton's summit 13,775'
↓Mountain-Forecast.com↓
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
MountainWeather.com 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
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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
http://mesowest.utah.edu/cgi-bin/droman/meso_base_dyn.cgi?stn=TETWY&unit=0&time=LOCAL&product=&year1=&month1=&day1=00&hour1=00&hours=24&graph=0&past=0&order=1
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.


http://www.wpc.ncep.noaa.gov/national_forecast/natfcst.php
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. In 2017, MDT starts on Sunday, March 12 and will end at 2:00 AM on Sunday, November 5.


Our local MountainWeather.com 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.


http://www.cpc.ncep.noaa.gov/products/predictions/610day/interactive/index.php


http://www.cpc.ncep.noaa.gov/products/predictions/610day/interactive/index.php
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

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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





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~ 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 by noon and get off the mountain by 2 p.m. Between June and September, summit temperatures can swing from the single digits to the 60's but shaded temperatures in the 30's are the most common when people are climbing in the morning.

Obviously, the temperature 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 foggy or wet conditions. Additionally, thick fog can make route finding difficult and hide incoming weather.

It is not uncommon for overnight temperatures to drop below freezing after a storm during the summer. 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. Thin ice can be shattered with a loose rock (or this) if you run into a problem area. Some free-soloing climbers will carry a rope for emergencies; sometimes a short thin rope.


~ The Weather Forecast ~


Obviously, 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 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 but the odds are good that a short shower will appear somewhere in the Tetons. As we all know, a 70% chance of bad weather may never materialize while a 20% chance of bad weather does.

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 rainfall. "Scattered" refers to the range of 30% to 50% coverage. Neither refers to intensity, amount, or time. The NWS does forecast a rain quantity in the hourly forecast graph and if you run your mouse over the graph, you will see hourly percentages at the bottom of the graphs.

The NWS's recreational forecast for GTNP has a long history of inaccurate temperature & wind predictions for the Lower Saddle & the summit. 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. Wind speeds can be off by a factor of 2. 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 NWS's recreational forecast is only available during the summer months.

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.


http://forecast.weather.gov/MapClick.php?lat=43.739&lon=-110.8018&unit=0&lg=english&FcstType=graphical
 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 weather comes from the west. The localized Wyoming weather radar doesn't properly cover the Teton Range.

Local meteorologist Jim Woodmency runs mountainweather.com. 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.


~ 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. 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.

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.


https://gacc.nifc.gov/gbcc/dispatch/wy-tdc/documents/information/education-prevention/backcountry_lightning_opt.pdf
Entire PDF on Lightning Safety
The PDF says that gullies are better than ridges for avoiding lightning.
During a storm, gullies can be deadly due to the runoff.


~ 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
Temps at Grand Targhee (9260' / 7 miles WNW)
Temps at Lava Mtn (10,371' / 39 miles E)
Temps at Togwotee Pass (9580' / 38 miles E)
Temps at Grouse Mountain (10380' / 27.3 miles E)
Nearby Stations
Teton County's Weather Station


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 ~


Windy.


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 WYWebcam index
Grand Teton Webcams


~ Weather Contacts ~


GTNP Weather Line: 307.739.3611

National Weather Service - Riverton
Western and Central Wyoming
1-800-211-1448
12744 West U.S. Hwy 26
Riverton, WY 82501
307-857-3898


~ Typical Temperature Differences ~


https://en.wikipedia.org/wiki/Lapse_rate


There are days 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, the National Weather Service will almost always forecasts a 8°F difference between the Lower Saddle and summit no matter what the weather or time of day. And their low-temperature difference between the valley floor and the summit is rarely more than 13°.


http://wyomingwhiskey.blogspot.com/p/owen-spalding-route-august-9th-2015.html
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. 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.

You can rent crampons and axes 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 the rental locations. Summer climbers can sometimes get by with less costly traction devices or winter running shoes with integrated traction. Shoulder-season climbers should be prepared to travel with an ice axe and crampons.


~ Historical Weather Patterns ~


https://weatherspark.com/averages/30628/Jackson-Hole-Wyoming-United-States
Historical Weather 1958-2012 GTNP (not Jackson)





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 ~


http://mesowest.utah.edu/cgi-bin/droman/past_dyn.cgi?stn=TETWY&hour1=9&day1=6&month1=11&year1=2015&product=&time=LOCAL&unit=0&order=1
 Lower Saddle Temperatures Summer 2015 -11,600'


http://www.mountainweather.com/jackson-hole/jackson-hole-weather-observations/
 Lower Saddle Temperatures Summer 2016 - 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.


http://mesowest.utah.edu/cgi-bin/droman/past_dyn.cgi?stn=TETWY&hour1=9&day1=6&month1=11&year1=2015&product=&time=LOCAL&unit=0&order=1
Lower Saddle Wind Speeds Summer 2015 - 11,600'


http://www.mountainweather.com/jackson-hole/jackson-hole-weather-observations/
 Lower Saddle Wind Speeds Summer 2016 - 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.


https://en.wikipedia.org/wiki/Wind_chill
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.


~ Grand Teton Webcams ~

Dornan's webcam inside GTNP.
Live Streaming - YouTube
Check the Time & Date. It may be an old image.
YouTube Channel

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.


Jackson Hole Golf & Tennis
South of the Airport in GTNP.
Check the Time & Date - It may be an old image.
Live Streaming - YouTube
YouTube Channel


Teton Valley, Idaho webcam - looking east.
View of Grand, Middle, and South Tetons.
Try the Live Streaming if the image is dark.
Live Streaming - YouTube
YouTube Channel

TetonCam.com - Idaho


Spring Creek Ranch atop the
East Gros Ventre Butte
Live Streaming - SeeJH


Current Visibility in Grand Teton National Park
This graph is often offline or malfunctioning. Direct Link to visibility numbers
AVALANCHE FORECAST
Click on the forecast area to see the latest forecast. — No off-season forecast —


Enjoy Safe Climbing

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