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

Heavy Rainfall Possible in the Upper Midwest, South Texas, and Puerto Rico and the Virgin Islands

Scattered thunderstorms and heavy rainfall may bring areas of flooding though the weekend over the Upper Midwest. A tropical disturbance will bring moderate to locally heavy rain to portions of South Texas into Saturday. Tropical Storm Erin may bring isolated flash and urban flooding, landslides or mudslides, and tropical storm conditions to Puerto Rico and the U.S. Virgin Islands. Read More >

Hazardous Weather Conditions

Current conditions at

Custer, Custer County Airport (KCUT)

Lat: 43.73°NLon: 103.62°WElev: 5600ft.

Fair

59°F

15°C

Humidity 75%
Wind Speed Calm
Barometer 30.11 in (1012.2 mb)
Dewpoint 51°F (11°C)
Visibility 10.00 mi
Last update 15 Aug 6:53 am MDT
Extended Forecast for

Keystone SD

  • Today

    Today: A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 84. Calm wind becoming east around 5 mph in the morning. Winds could gust as high as 20 mph.

    High: 84 °F

    Mostly Sunny
    then Slight
    Chance
    T-storms

  • Tonight

    Tonight: A 30 percent chance of showers and thunderstorms, mainly before 11pm. Mostly cloudy, with a low around 65. East wind around 5 mph becoming calm in the evening. Winds could gust as high as 15 mph.

    Low: 65 °F

    Chance
    T-storms then
    Mostly Cloudy

  • Saturday

    Saturday: A 50 percent chance of showers and thunderstorms, mainly after noon. Partly sunny, with a high near 80. Calm wind becoming east around 5 mph in the morning. Winds could gust as high as 20 mph.

    High: 80 °F

    Slight Chance
    T-storms then
    Chance
    T-storms

  • Saturday Night

    Saturday Night: A 30 percent chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 62. East wind around 5 mph becoming calm in the evening. Winds could gust as high as 15 mph.

    Low: 62 °F

    Chance
    T-storms then
    Partly Cloudy

  • Sunday

    Sunday: A 30 percent chance of showers and thunderstorms after noon. Mostly sunny, with a high near 84. Calm wind becoming southeast around 5 mph in the afternoon. Winds could gust as high as 15 mph.

    High: 84 °F

    Mostly Sunny
    then Chance
    T-storms

  • Sunday Night

    Sunday Night: A 20 percent chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 62. East wind around 5 mph becoming calm in the evening. Winds could gust as high as 15 mph.

    Low: 62 °F

    Slight Chance
    T-storms then
    Mostly Clear

  • Monday

    Monday: A 20 percent chance of showers and thunderstorms after noon. Sunny, with a high near 84. Calm wind becoming southeast around 5 mph in the afternoon. Winds could gust as high as 15 mph.

    High: 84 °F

    Sunny then
    Slight Chance
    T-storms

  • Monday Night

    Monday Night: A slight chance of showers and thunderstorms before midnight. Mostly clear, with a low around 63. East wind around 5 mph becoming west after midnight. Winds could gust as high as 15 mph.

    Low: 63 °F

    Slight Chance
    T-storms then
    Mostly Clear

  • Tuesday

    Tuesday: A slight chance of showers and thunderstorms after noon. Sunny, with a high near 86.

    High: 86 °F

    Sunny then
    Slight Chance
    T-storms

Detailed Forecast

Today
A 20 percent chance of showers and thunderstorms after 1pm. Mostly sunny, with a high near 84. Calm wind becoming east around 5 mph in the morning. Winds could gust as high as 20 mph.
Tonight
A 30 percent chance of showers and thunderstorms, mainly before 11pm. Mostly cloudy, with a low around 65. East wind around 5 mph becoming calm in the evening. Winds could gust as high as 15 mph.
Saturday
A 50 percent chance of showers and thunderstorms, mainly after noon. Partly sunny, with a high near 80. Calm wind becoming east around 5 mph in the morning. Winds could gust as high as 20 mph.
Saturday Night
A 30 percent chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 62. East wind around 5 mph becoming calm in the evening. Winds could gust as high as 15 mph.
Sunday
A 30 percent chance of showers and thunderstorms after noon. Mostly sunny, with a high near 84. Calm wind becoming southeast around 5 mph in the afternoon. Winds could gust as high as 15 mph.
Sunday Night
A 20 percent chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 62. East wind around 5 mph becoming calm in the evening. Winds could gust as high as 15 mph.
Monday
A 20 percent chance of showers and thunderstorms after noon. Sunny, with a high near 84. Calm wind becoming southeast around 5 mph in the afternoon. Winds could gust as high as 15 mph.
Monday Night
A slight chance of showers and thunderstorms before midnight. Mostly clear, with a low around 63. East wind around 5 mph becoming west after midnight. Winds could gust as high as 15 mph.
Tuesday
A slight chance of showers and thunderstorms after noon. Sunny, with a high near 86.
Tuesday Night
Mostly clear, with a low around 64.
Wednesday
Sunny, with a high near 89.
Wednesday Night
Mostly clear, with a low around 66.
Thursday
Sunny, with a high near 88.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Keystone SD
 43.87°N 103.4°W (Elev. 4413 ft)
Last Update:
6:28 am MDT Aug 15, 2025
Forecast Valid:
7am MDT Aug 15, 2025-6pm MDT Aug 21, 2025
 
Forecast Discussion
 
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Additional Resources

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation