Grand Teton Forecast Wednesday -Thursday August 18-19

  • 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.

September weather in mid-August

Thunderstorms, lightning, and an increasingly cold rain 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. Snow levels may drop to 9500 – 10,000 feet by Thursday afternoon.

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 low to mid 60’s in the morning, falling to the upper 50’s by afternoon.

Thursday: Cloudy with rain and showers continuing. Accumulating snows likely in the high elevations to the east and southeast (Wind River Range) of the Park. Snow levels in the Park falling to 9500-10,000 feet by afternoon. Some accumulation possible on Paintbrush Divide. Becoming breezy in the afternoon with northerly winds gusting 20-25 mph. Cool, with high temperatures around 60 deg.

Smoke forecast: Despite the rain, associated cold front, and northerly winds, the smoke from the western fires will continue to cover northwest Wyoming. Expect moderate to occasionally heavy smoke in the Park both Wednesday and Thursday.

Extended Outlook:

Friday: Rain and showers diminishing after midday, becoming partly cloudy by afternoon. Highs in the mid-60’s.

Saturday: Variable cloudiness in the morning with rain and showers developing in the afternoon. Highs near 70 degrees.

Sunday: Mostly cloudy with periods of rain and rain showers. Highs in the upper 60’s.

Monday: Partly to mostly sunny in the morning and variable cloudiness in the afternoon. Rain showers should stay to the north of the Park. Warmer, with highs in the low to mid 70’s.

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

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