Grand Teton Forecast Tuesday – Wednesday August 17-18

  • Short-term forecast, emphasizing weather parameters most important to visitors in the Jenny Lake / String Lake / Leigh Lake region
  • Animations of expected weather radar updated daily.
    • Other weather parameters (snow, wind, etc.) added when they may be significant.
    • For orientation, animation maps show Wyoming and a small portion of the surrounding states.
  • Temperature graphic is for the Airport. Subtract a couple of degrees for String Lake and 3-5 degrees if a visitor asks about Colter Bay.
  • The wind gusts forecasts are usually (in the summer) a reasonable forecast for average sustained wind speeds at 9,000 – 11,000 feet for backcountry hikers.
  • For those with access to Grand Teton Park Radios: Channel 16 is NOAA Weather Radio
  • Click here for access to the NOAA smoke-forecasting site.
  • Click here for an animation of smoke concentration over the northwest U.S. for the next two days.

Big changes ahead…

Hazardous boating conditions on Leigh Lake Tuesday midday through evening. Winds gusting to 35 mph+. Whitecaps and waves up to 1 foot.

Backcountry campers and hikers should be prepared for high winds Tuesday afternoon. Thunderstorms, lightning, and an increasingly cold rain start Tuesday evening, and continue through Wednesday into Thursday. Expect extensive fog and clouds in the mountains Wednesday and Thursday. By Thursday, temperatures in the mountains will be in the 30’s and 40’s. Rain may mix with snow at the highest elevations on Thursday.

Tuesday: Partly cloudy with widely scattered showers and thunderstorms developing by mid-afternoon. Showers and thunderstorms becoming more numerous Tuesday night. Increasing winds, with gusts from the southwest 25-35 mph between midday and evening. Winds may gust to 45+ mph above 9000 feet in afternoon. Warm with highs in the mid-80’s.

Wednesday: Mostly cloudy with periods of rain, showers, and an occasional thunderstorm. Generally light winds except in the vicinity of thunderstorms. Much cooler with highs in the upper 60’s.

Smoke forecast: Despite the rain and associated cold front, it will take a while for the smoke to clear out. Expect moderate to heavy smoke on Tuesday and light to moderate smoke on Wednesday.

Extended Outlook:

Thursday: Cloudy with rain and showers continuing. Cool, with high temperatures around 60 deg. Accumulating snows possible in the highest elevations to the east and southeast (Wind River Range) of the Park.

Friday – Sunday: Variable cloudiness and unsettled, with occasional showers and an isolated thunderstorm. Highs in the mid-60’s on Friday and around 70 deg on Saturday and Sunday.

Monday: Partly to mostly sunny. Highs in the mid 70’s.

2 thoughts on “Grand Teton Forecast Tuesday – Wednesday August 17-18

  1. thank you, dave! your forecasts are so clear and precise. i especially appreciate your insights about water activities on leigh lake… i’ve experienced the “paintbrush canyon” fury and it’s nothing to fool with!
    take good care.. .best to you and cathy.

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