Grand Tetons Weather

This is info for the De Anza College Outdoor Club trips to Grand Teton National Park, Wyoming. The main trip information page is at Grand Tetons . The trip pages index is at: Grand Tetons trip pages index

 

NPS photo Teton storm:

Watch a Grand Teton National Park summer weather video:

http://www.nps.gov/grte/photosmultimedia/tp.htm

rain on windshield: big drops of rain on windshield

National Park Service stats (temperatures and precipitation by month) for Moose, Wyoming
chart of temperatures and preciptation by month Moose Wyoming, Grand Teton National park

Most of our club trips are in the late summer / early fall. Nights and early mornings are cold.

Aug. 11 average high temp 78/ average low temp 44,
Aug. 21 average high temp 76/ average low temp 43
in the lower elevations of the park, at least 5 degrees colder on the upper elevation trails.

Probability of precipitation: Aug. 11 16%, Aug. 21 15%

There is usually a big temp difference at different altitudes. One forecast had highs of 75 degrees in the valley at 6,000 feet elevation, 68 degrees at 8,000 feet and 60 degrees at 10,000 feet. Another forecast had 68 degrees in the valley at 6,000 feet, 61 degrees at 8,000 feet and 53 degrees at 10,000 feet.

Overnight lows can be 48 degrees in the valley at 6,000 feet elevation, 45 degrees at 8,000 feet and 39 degrees at 10,000 feet. Another forecast had 47 degrees in the valley at 6,000 feet, 41 degrees at 8,000 feet and 32 degrees at 10,000 feet.

Hiking trails:
The park service says: Grand Teton/Jackson Hole “Valley trails are often snow covered until late May.” “Snow melts gradually, leaving valley trails by mid-June, canyon trails by mid-July.” “Many mountain passes remain snow covered throughout most of the summer and an ice axe, and the ability to use it, may be recommended to ensure safe travel… Consider bringing an ice axe through mid-july and know how to use it to self-arrest and self-belay on snow. Snowfield crossings can be extremely hazardous and are the source of serious accidents in the Tetons.”

The National Weather Service warns:

” Myth: If it’s not raining or there aren’t clouds overhead, you’re safe from lightning.
Fact: Lightning often strikes more than three miles from the center of the thunderstorm,
far outside the rain or thunderstorm cloud.
“Bolts from the blue” can strike 10-15 miles from the thunderstorm.

towering clouds

Afternoon thundershowers are common in the summer and into fall. During a thunderstorm, don’t take a shower or use a sink, including washing dishes. Don’t swim. Don’t talk on a land line phone. Don’t use your I pod. Don’t get zapped! People have died inside buildings during thunderstorms. Please read Thunderstorm and lightning safety

 

Here, a multi-mile-wide rainstorm and potential thunderstorm cloud over Jackson lake
as seen from Hanging Canyon trail:
rain falling onto lake from huge cloud

My 1965 copy of A Climber’s Guide to the Teton Range warns “The Tetons are big mountains, big enough to make their own weather, to hide some of the early signs of changing weather… very severe storms can come up quickly. Be equipped for them – this includes reserve food and warm clothing… The one regularity of Teton weather is that the storms almost always come from the southwest. This characteristic means that there is usually very little warning of an approaching storm for climbers on the north and northeast sides of the peaks. It should be kept in mind that these storms can sometimes be quite severe; the driving sleet or snow can convert an ordinary climb into a fight for life.”
photo by Alanna Klassen clouds: dark clouds at top, lighter belowdark and light clouds
When it rains in the flats it may snow up near the peaks; at least one period of interesting weather with snowfall at the higher elevations occurs in late August every year. Cold early mornings and overnights could bring a few snow flakes to lower elevations even in August, the warmest month. The park warns: “Low temperatures at the high elevations may be at or below freezing at any time of the year.”

tops of trees, rainbow behind

Thunderstorms sometimes have hail. You may have heard that Wyoming, Nebraska, and Colorado, usually have the most hailstorms and the area where the three states meet, “hail alley,” has not only the most hail, but the most damaging hail.

Hail Alley, Wyoming is hundreds of miles away from Grand Teton.

 

We watch the weather reports closely and often track thunderstorms as they approach us. One day heavy rain and / or potentially large-sized hail, the size that can crack a windshield, was forecast, so we put two sleeping pads on the windshield under the wipers with a couple of straps tied across and through the shut car doors (the wind was coming up fast as we installed this.)

The hail did not materialize.

two sleeping pads across a windshield

 

One year we had a light dusting of snow and tiny hail in the lower elevation where we camp, (didn’t need chains for the cars so far but we have always brought them, even for the four wheel drive vehicles with snow tires).

If you intend to drive a convertible and it has an electric power top, be sure you know how to put the top up manually in case the push-button function stops working. Rain storms can come in quickly and heavily. You should have alternate ways to get around if lightning is forecast, because
you are not safe during lightning in a convertible.
“The only safe place is inside a substantial building or hard-topped vehicle.”

We’ve also had lots of late summer / early fall days sunny enough for swimming in a lake if you are intrepid (or if you wear a couple of pairs of jammers or wear a springsuit size wetsuit or, okay, your triathlon wetsuit).

Below, Eric Marxmiller, Michael Gregg, Alan Ahlstrand, Mouzhan Yousefi, Duong Nguyen and Raquel Garza:

swimming in String Lake 400 pixels:

and when it is clear: view of the Milky Way through a tent door:

milky way seen framed by tent door

The local weather report almost always predicts at least a slight chance, or more likely a 20% chance of a thunderstorm, even if none show themselves to us. A report of possible “isolated showers and thunderstorms” also almost always says that “some storms could produce gusty winds” or “some storms could produce small hail and gusty winds.”

In September 2000 we had some thunderstorms  and occasionally long bouts of rain. (We kayak/canoe in the rain and wind, but not during thunderstorms.)

Thunderstorms can have 0.40 inches of rain in less than an hour, or that much in 24 hours.

In 2002 we just missed a previous 2.4 inches of rain in three days and it didn’t rain on us at all until the last morning. The last two nights of the 2004 trip we were woken by heavy rain around midnight and had drizzle/rain and occasional downpours during the last two days. 2007 we had two evenings of magnificent local lightning displays, one of which sent the campers into one of our rental cabins for safety.

People on the 2005 trip said, after the kayaking overnight, that they didn’t think I stressed the probability of cold nights enough.

Lake Solitude hikers with early fall snow 2006:
In September 2005 and 2007 it snowed on our hikers at Lake Solitude and rained on those lower down in Cascade Canyon.

In 2007 one long evening-into-night storm had lightning as often as three hits in ten seconds with heavy rain that flooded streets in Jackson, Wyoming.

In 2010 we had many rainy or drizzly days and it did not snow on us but we did wake up to snow covered mountains near the end of the trip:

Grand teton peaks with heavy clouds above

September 10, 2010 was the first big snow storm with a foot or so of snow at 9,000 feet elevation.

 

mountains with dark clouds above
A typical late summer rain storm we experience at Colter Bay in Grand Teton National Park
might have big white puffy clouds against a very blue sky through the morning
that change in the afternoon to gray clouds going by as the wind picks up,
at first ruffling the Aspen Leaves, then later moving the pine branches
and later the smaller diameter trees start to sway
and occasionally, with more wind, the windows of your cabin start to rattle.
There might be a moment of large raindrops, then a sudden downpour.
The heavy rain, with at first distant lightning strikes miles to the south and east, followed by closer-in lightning strikes
(one evening for example, one at the shore of Emma Matilda Lake, one near the east of the road junction at Colter Bay and the highway, then in the middle of the north end of Jackson Lake).

This might only last 25 minutes. Then the storm can stop for an hour or so and resume later.
Or heavy downpours and lightning strikes can last for many hours.

An hourly weather report you are looking at might say “Intermittent clouds” for all hours, then change to “Intermittent clouds” for most hours, but add in “4pm Mostly cloudy w/ t-storms,” then the next time you look it switches to “5pm Mostly cloudy w/ t-storms,” then” 6pm Mostly cloudy w/ t-storms,” and then the thunder and lightning appears.
Some lightning strikes sound louder and closer because they reflect off the mountains.

How can you tell where the lightning strikes are that you hear the thunder from, (or might actually see a visible bolt)?

Lightning strikes in the last 24 hours are recorded at:

http://www.lightningmaps.org/?lang=en#y=43.7707;x=-108.2102;z=7;t=1;m=oss;r=0;s=0;o=0;b=27.83;n=0;d=2;dl=2;dc=0;ts=0;

https://www.lightningmaps.org/blitzortung/america/index.php?lang=en

https://www.accuweather.com/en/us/national/severe-weather-maps

clouds above tree tops

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ALWAYS bring your hooded waterproof rain jacket and rain pants, warm clothes for under it

and for paddling borrow a dry bag from the club advisor (warning: she might not have that many so you will need the share) as we do not turn back when rain starts unless there is a thunderstorm, and your rain suit can help keep you warm if there is wind. Advice on gear.
You should also plan for other camera, etc. waterproofing, when out sightseeing and hiking.

(Weather could cancel kayaking as we never risk kayaking during thunderstorms.)

rainbow in distance

Jackson Hole weather, usually also including a 10,000 foot forecast and forecast of lightning:

https://www.mountainweather.com/jackson-hole/jackson-hole-forecast/

Yellowstone:

https://www.mountainweather.com/jackson-hole/yellowstone-park/

Yellowstone National park has a live weather display
https://www.nps.gov/features/yell/kiosk/weather.html

brief weather descriptions

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Teton peaks with clouds and rain falling

sunlight streaming through clouds teton range Sept 2011 300 pixels: photo mostly of clouds with a mountain range in the distance and little light on a lake in the mid distance

wettest months: May, June, Dec. and March

warmest (average highs): Aug, July, June, Sept, May

coldest (average highs): Jan, Dec, Feb, (in single digits) March, Nov. (in the teens)

and yet another source said that in the town of Jackson, January is the snowiest month, May the wettest; hottest recorded temp 98 (more likely a 89 to 90 degree max), coldest 63 below zero (more likely a -9 to -10 degree minimum).

NPS photo rainbow over hayden valley yellowstone:

ripples from drops on water

 

– Glacier National Park said about biking in cold / rain:

“Windbreakers or rain shells over thin insulated jackets are good layers to bring for possible inclement weather conditions.

A thin, neoprene hat will help keep your head warm, and it will fit under a helmet.

Gloves and neck gaiters assist greatly with retaining warmth.

Bring additional dry and warm layers for after your ride.”

Neoprene is a close-cell synthetic-rubber material that is commonly used in wetsuits and to make an extra thick swim cap an open-water triathlete might wear: closed-cell 3 millimeters thick. Look for a flexible chin strap or you can buy one without a chin strap.

It should fit comfortably under your bike helmet (and climbing helmet) and not interfere with the proper fit of your helmet or your peripheral vision.

 

There are crucial things wrong with each of these tents.

Don’t buy a cheap tent has reasons why and more examples of tents to NOT use in the rain.

Find more advice about tents and rain gear here.

 

long row of clouds

What kind of clouds are those? Pictures of Cirrus, Cirrostratus, Cirrocumulus, Stratus, Altostratus, Nimbostratus, Stratocumulus, Cumulus, Altocumulus, Cumulonimbus and Lenticular clouds

are at:

https://www.nps.gov/common/uploads/teachers/lessonplans/Cloud%20Cards%2020191.pdf

 

SNOW IN THE SUMMER at higher elevations?

“AUGUST 24, 2013 Overnight moisture and cold temperatures brought a wintry mix to parts of the Tetons. At the Lower Saddle the 6:00 am. temperature was 36 degrees.”

July 11, 2016 there was a generous coating of snow in the high country. The Jenny Lake climbing rangers blog said:

“JULY SNOW STORM! – JULY 10-11,2016

4” of new snow reported at the Lower Saddle along with 50-70mph gusts. The fixed lines and watering hole were encased in ice – similar to current conditions up high in the mountains. Expect “alpine” conditions for the next number of days, particularly in the east to north to west facing terrain as well as the sheltered terrain and ledges of the southerly terrain.”

And the Jenny Lake climbing rangers blog had this warning June 10, 2016:

“Generally, there is snow in the high country till mid July. This includes the Teton Crest Trail. Until the beginning of July this snow may be punchy, except very early in the morning and during the night. This type of hiking (post-holing) is type II character building. It is not fun in the traditional sense.”

You may be up for the challenge,
but sincerely ask yourself if everyone in your party feels the same way.

North and East facing passes can hold snow even longer.

Until enough intrepid backpackers have created a trail of hard packed snow, strong navigation skills are a necessity.”

Wind storms can be severe, even in the summer. A June 1, 2015 trees downed by a wind storm stranded visitors on many roads. Park Rangers, road and fire crews cleared over 150 trees. Microbursts of wind at 52 and 56 mph were recorded.

Again, from the the Jenny Lake climbing rangers blog

“FLASH FLOOD IN PAINTBRUSH CANYON – August 14, 2014

Yesterday afternoon a flash flood occurred in Paintbrush Canyon affecting four different sections of trail in the vicinity of the switch backs leading out of the Lower Paintbrush camping zone. Be prepared for walking on uneven surfaces, multiple creek crossings and debris that may have not yet stabilized. Extremely heavy rain preceded the event. Considering the large amount of heavy rain the Tetons have recently received, there is increased risk of rock fall everywhere and the chance of additional flash flooding if these conditions persist. As is commonly said in the avalanche world, uncommon conditions create uncommon events. In the event of heavy rain, head to high ground and avoid creek bottoms.”

strip of a photo of mountains with some snow

Winter lasts about six or seven months in the Grand Teton, Jackson Hole area. One source had the snowiest months: Jan, Dec, Feb, Nov, March. Another source said: The most snow, in this order: February, March, January, December, April, November. Grand Teton park says that “the first heavy snows fall by November 1 and continue through March; snow and frost are possible during any month.”

One blogger described ‘nine months of winter and three months of bad skiing.’

Watch a Winter Safety in Grand Teton video:

http://www.nps.gov/grte/photosmultimedia/tp.htm

sign frequent heavy drifting: a road sign that says frequent heavy drifting (of snow) can be expected teton road with blowing snow: teton road with two cars and blowing snow Snow generally covers roads from early November through mid-April. Blowing snow is frequent in the winter, even to the extent that you can’t see very far in front of your vehicle. Cloud cover can prevent you from seeing the mountains for days at a time, even within a few miles of the range.

teton park road winter nps photo: cross country skier on snowy road with mountains in background The inner park road is closed from just beyond the Taggart Lake parking lot all the way to Signal Mountain (and not plowed) from November 1 over the winter until sometime around May 1. Once snow accumulates the road is used for cross-country skiing, skate skiing and snow-shoeing.

Grand Teton park recommends vehicles with four-wheel drive or all weather tires and warns that all roads can be closed during blizzards. “Winter driving can be challenging; park roads are often covered with ice or hard packed snow; winter storms can create white-out driving conditions.”

nps photo SUV hit sign: nps photo snowy road, SUV with a crumpled hood hit sign

Bison and other animals use the plowed highways to move more easily than in the deep snow, and motorists need to drive slowly. https://www.nps.gov/grte/learn/news/bison-on-roads-motorists-warned-to-be-alert-and-slow-down.htm

3 bison on a snowplowed road

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WY_SchwabacherLanding12 copyright EJ Peiker: mountain peak with dark clouds above

photo above © E J Peiker http://www.ejphoto.com/grand_teton_page.htm used with permission

The National Park service has these weather factoids:

“Crickets are accurate thermometers; they chirp faster when warm and slower when cold. They are extremely accurate. Count their chirps faster for fourteen seconds, then add forty, and you have the temperature (in Fahrenheit) of wherever the cricket is.”

“Human hair, especially blond hair, has a tendency expand in length as the humidity rises. This may cause naturally-curly hair to droop. Or it may cause straight hair to curl up a little. The higher the humidity, the more likely it is to rain.”

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For details about our next club trip to Grand Teton National Park, go to: Grand Tetons.

Grand Tetons trip pages index has brief descriptions of most of the pages about this trip.

Grand Tetons kayaking

Grand Tetons sightseeing

Your Safety in Grizzly Bear Territory tells you what to do if you see a bear in the distance or a bear charges you and has info about Bear Pepper Sprays and what might happen before a bison charges.

pink clouds above tree tops

Grand Teton Backpacking

Backpacking Advice includes:

Must bring for each large group (or perhaps for each couple or person)

Must bring backpacking for each person

Some (crazy?) people think these are optional for backpacking:

Backpacking luxuries(?)

Do not bring these backpacking

To keep down on weight backpacking

Don’t rush out and buy

BACKBACKING FOOD

Low-cook backpacking foods

Leave no trace camping has these basic principles:
Plan Ahead and Prepare
Travel and Camp on Durable Surfaces
Dispose of Waste Properly
Minimize Campfire Impacts
Respect Wildlife
Be Considerate of Other Visitors

examples and details of how easy this can be are at: Leave no trace
darkclouds at top, some sunset light below