National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Dangerous Heat and Heavy Rainfall into the Weekend

Hot temperatures and high humidity are forecast to continue across the mid-Mississippi Valley into this weekend. Heat Advisories remain in effect. Heavy to excessive rainfall occurring at times through the weekend could bring areas of flooding to parts of the northern Rockies, upper Midwest, central Great Lakes, and southern New England. Read More >

Hazardous Weather Conditions

Current conditions at

Riverton Regional Airport (KRIW)

Lat: 43.06219°NLon: 108.44701°WElev: 5443.0ft.

Clear

59°F

15°C

Humidity 64%
Wind Speed NW 6 MPH
Barometer 30.14 in (1020.66 mb)
Dewpoint 47°F (8°C)
Visibility 10.00 mi
Last update 18 Sep 08:53 PM MDT
Extended Forecast for

Arapahoe WY

  • Tonight

    Tonight: A 20 percent chance of showers and thunderstorms before 2am. Patchy fog after 4am. Otherwise, mostly cloudy, with a low around 51. West northwest wind 3 to 6 mph.

    Low: 51 °F

    Slight Chance
    T-storms and
    Patchy Fog

  • Saturday

    Saturday: A 50 percent chance of showers and thunderstorms, mainly after 4pm. Patchy fog before 9am. Otherwise, mostly sunny, with a high near 71. Calm wind becoming north northwest 5 to 9 mph in the afternoon. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 71 °F

    Chance
    Showers and
    Patchy Fog

  • Saturday Night

    Saturday Night: Showers likely and possibly a thunderstorm before 1am, then a chance of showers. Patchy fog after 2am. Otherwise, mostly cloudy, with a low around 46. North northeast wind 6 to 11 mph becoming light and variable after midnight. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 46 °F

    Showers
    Likely and
    Patchy Fog

  • Sunday

    Sunday: A chance of showers, with thunderstorms also possible after noon. Partly sunny, with a high near 65. Calm wind becoming northeast around 6 mph in the afternoon. Chance of precipitation is 30%.

    High: 65 °F

    Chance
    Showers then
    Slight Chance
    T-storms

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 44. Northeast wind around 6 mph becoming calm in the evening.

    Low: 44 °F

    Partly Cloudy

  • Monday

    Monday: Sunny, with a high near 71. Calm wind becoming east northeast around 6 mph in the afternoon.

    High: 71 °F

    Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 45. North northeast wind around 6 mph becoming west after midnight.

    Low: 45 °F

    Mostly Clear

  • Tuesday

    Tuesday: Mostly sunny, with a high near 77.

    High: 77 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: A 20 percent chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 48.

    Low: 48 °F

    Slight Chance
    T-storms then
    Partly Cloudy

Detailed Forecast

Tonight
A 20 percent chance of showers and thunderstorms before 2am. Patchy fog after 4am. Otherwise, mostly cloudy, with a low around 51. West northwest wind 3 to 6 mph.
Saturday
A 50 percent chance of showers and thunderstorms, mainly after 4pm. Patchy fog before 9am. Otherwise, mostly sunny, with a high near 71. Calm wind becoming north northwest 5 to 9 mph in the afternoon. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Saturday Night
Showers likely and possibly a thunderstorm before 1am, then a chance of showers. Patchy fog after 2am. Otherwise, mostly cloudy, with a low around 46. North northeast wind 6 to 11 mph becoming light and variable after midnight. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Sunday
A chance of showers, with thunderstorms also possible after noon. Partly sunny, with a high near 65. Calm wind becoming northeast around 6 mph in the afternoon. Chance of precipitation is 30%.
Sunday Night
Partly cloudy, with a low around 44. Northeast wind around 6 mph becoming calm in the evening.
Monday
Sunny, with a high near 71. Calm wind becoming east northeast around 6 mph in the afternoon.
Monday Night
Mostly clear, with a low around 45. North northeast wind around 6 mph becoming west after midnight.
Tuesday
Mostly sunny, with a high near 77.
Tuesday Night
A 20 percent chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 48.
Wednesday
Sunny, with a high near 78.
Wednesday Night
Mostly clear, with a low around 47.
Thursday
Mostly sunny, with a high near 80.
Thursday Night
Partly cloudy, with a low around 48.
Friday
Mostly sunny, with a high near 81.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Arapahoe WY
 42.97°N 108.49°W (Elev. 5036 ft)
Last Update:
8:47 pm MDT Sep 18, 2026
Forecast Valid:
9pm MDT Sep 18, 2026-6pm MDT Sep 25, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation