Union County, SD Weather Forecast
County weather hub
Chance Showers And Thunderstorms
Compare major city weather across Union County, scan the latest forecast snapshots, and jump into local 7-day outlook pages from one hub.
A chance of showers and thunderstorms. Some of the storms could be severe. Partly sunny. High near 89, with temperatures falling to around 81 in the afternoon. South southeast wind 15 to 20 mph, with gusts as high as 30 mph. Chance of precipitation is 50%. New rainfall amounts between a quarter and half of an inch possible.
County Weather Overview
This county weather page brings together forecast coverage for Union County so visitors can compare temperatures, wind, and conditions across the region without hopping between unrelated pages.
Current forecast coverage spans 3 of 3 mapped cities in Union County.
Page Snapshot
- Page focus
- county weather
- Forecast window
- May 17 to May 23, 2026
- Latest sync
- May 17, 2026 5:57 PM CDT
- Forecast office
- FSD
- Source
- NOAA / NWS
Daily Outlook
This Week in Union County
This Afternoon looks like the warmest upcoming period in Union County at 89 degrees F.
Tuesday Night is the coolest period ahead with temperatures near 35 degrees F.
The strongest winds are forecast for This Afternoon at about 15 to 20 mph SSE.
Precipitation is mentioned in 10 upcoming forecast periods.
Forecast Details
- Last updated
- May 17, 2026 5:57 PM CDT
- Coverage
- 7 days
- Time zone
- America/Chicago
- Forecast office
- FSD
- Radar station
- KFSD
Weather data is provided by the National Weather Service and refreshed automatically for U.S. locations.
Open NOAA sourceExtended Forecast
Showers and thunderstorms before 1am, then a chance of showers and thunderstorms between 1am and 2am, then a slight chance of showers and thunderstorms between 2am and 4am. Some of the storms could be severe and produce heavy rain. Cloudy. Low around 47, with temperatures rising to around 51 overnight. Northwest wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 100%. New rainfall amounts between three quarters and one inch possible.
A chance of rain showers between 10am and 1pm, then a chance of showers and thunderstorms between 1pm and 4pm, then a chance of showers and thunderstorms. Cloudy, with a high near 62. North wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 50%. New rainfall amounts between a tenth and quarter of an inch possible.
Showers and thunderstorms. Cloudy. Low around 40, with temperatures rising to around 44 overnight. North northwest wind 15 to 20 mph, with gusts as high as 30 mph. Chance of precipitation is 80%.
A slight chance of rain showers before 7am. Partly sunny, with a high near 59. Northwest wind 15 to 20 mph, with gusts as high as 30 mph. Chance of precipitation is 20%.
Partly cloudy, with a low around 35. North northeast wind 0 to 15 mph, with gusts as high as 25 mph.
Mostly sunny, with a high near 64.
Mostly cloudy, with a low around 42.
Partly sunny, with a high near 68.
A chance of showers and thunderstorms after 7pm. Mostly cloudy, with a low around 44. Chance of precipitation is 30%.
A chance of showers and thunderstorms. Partly sunny, with a high near 73. Chance of precipitation is 30%.
A chance of showers and thunderstorms. Partly cloudy, with a low around 49. Chance of precipitation is 40%.
A chance of showers and thunderstorms. Partly sunny, with a high near 79. Chance of precipitation is 40%.
A chance of showers and thunderstorms before 7pm, then a slight chance of showers and thunderstorms between 7pm and 1am. Partly cloudy, with a low around 53. Chance of precipitation is 30%.
Detailed Forecast
| Period | Conditions | Temp | Wind |
|---|---|---|---|
|
This Afternoon
May 17
|
Chance Showers And Thunderstorms
|
89°F |
15 to 20 mph
SSE
|
|
Tonight
May 17
|
Showers And Thunderstorms
|
47°F |
15 mph
NW
|
|
Monday
May 18
|
Chance Rain Showers then Chance Showers And Thunderstorms
|
62°F |
15 mph
N
|
|
Monday Night
May 18
|
Showers And Thunderstorms
|
40°F |
15 to 20 mph
NNW
|
|
Tuesday
May 19
|
Slight Chance Rain Showers then Partly Sunny
|
59°F |
15 to 20 mph
NW
|
|
Tuesday Night
May 19
|
Partly Cloudy
|
35°F |
0 to 15 mph
NNE
|
|
Wednesday
May 20
|
Mostly Sunny
|
64°F |
0 to 10 mph
SE
|
|
Wednesday Night
May 20
|
Mostly Cloudy
|
42°F |
5 to 10 mph
SSE
|
|
Thursday
May 21
|
Partly Sunny
|
68°F |
10 to 20 mph
SSE
|
|
Thursday Night
May 21
|
Chance Showers And Thunderstorms
|
44°F |
10 to 15 mph
SSE
|
|
Friday
May 22
|
Chance Showers And Thunderstorms
|
73°F |
10 to 15 mph
S
|
|
Friday Night
May 22
|
Chance Showers And Thunderstorms
|
49°F |
10 to 15 mph
SSE
|
|
Saturday
May 23
|
Chance Showers And Thunderstorms
|
79°F |
10 to 15 mph
S
|
|
Saturday Night
May 23
|
Chance Showers And Thunderstorms then Slight Chance Showers And Thunderstorms
|
53°F |
10 mph
SSE
|
Major City Forecasts
Live forecast snapshots for major cities across Union County.
Coverage
Forecast coverage currently spans 3 of 3 mapped cities in Union County.
Largest mapped city population in this region: 2,928.
