Union County, SD Weather Forecast for 5-Days

Updated: Sun May 10th 2026 7:00 AM CDT

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Union County, SD Weather – 5-10 – Sunny
74° / 41°
Sunny
Union County is set for a sunny day with temperatures peaking at 74°F and dipping to 41°F. Wind will be moderate, blowing around 11mph on average and gusts of 16mph at 11 PM. Humidity levels should be comfortable, sitting around 43% on average, the maximum being 63% at 8 AM and 22% being its lowest at 3 PM. Barometric pressure is its highest of 30.15inHg at 8 AM, a lowest point of 30.08inHg at 4 PM with an avg 30.12inHg.
Union County, SD Weather – 5-11 – Scattered Showers
82° / 49°

Weather Tomorrow

Scattered Showers
In Union County, showers likely at times with highs near 82°F and lows around 49°F. The chance of rain is 86% with an estimated 0.01in. Winds will be strong at speeds peaking at 21mph and gusts of 34.2mph at 10 PM. Humidity levels should be comfortable, sitting around 42% on average, the maximum being 50% at 8 AM and 30% being its lowest at 5 PM. Barometric pressure is its highest of 30.19inHg at 3 AM, a lowest point of 29.84inHg at 7 PM with an avg 30.03inHg.
Union County, SD Weather – 5-12 – Sunny
77° / 59°
Sunny
Bright and sunny conditions in Union County, with a high of 77°F and a low of 59°F. Winds will be strong at speeds peaking at 22mph and gusts of 31.4mph at 1 AM. Humidity levels should be comfortable, sitting around 38% on average, the maximum being 55% at 8 AM and 23% being its lowest at 5 PM. Barometric pressure is its highest of 30.06inHg at 10 PM, a lowest point of 29.79inHg at 3 AM with an avg 29.93inHg.
Union County, SD Weather – 5-13 – Sunny
78° / 50°
Sunny
Union County could see a sunny day with daytime highs of 78°F and nighttime lows near 50°F. Wind will be moderate, blowing around 11mph on average and gusts of 22.1mph at 11 PM. Humidity levels should be comfortable, sitting around 40% on average, the maximum being 62% at 7 AM and 24% being its lowest at 6 PM. Barometric pressure is its highest of 30.2inHg at 9 AM, a lowest point of 29.97inHg at 8 PM with an avg 30.1inHg.
Union County, SD Weather – 5-14 – Scattered Showers
90° / 59°
Scattered Showers
Union County may see passing showers, with daytime highs of 90°F and overnight lows near 59°F. The chance of rain is 88% with an estimated 0.03in. Winds will be strong at speeds peaking at 21mph and gusts of 27.1mph at 1 AM. Humidity levels should be comfortable, sitting around 49% on average, the maximum being 67% at 11 PM and 33% being its lowest at 4 PM. Barometric pressure is its highest of 30.02inHg at 1 AM, a lowest point of 29.64inHg at 7 PM with an avg 29.8inHg.
Union County, SD Weather – 5-15 – Scattered Showers
84° / 65°
Scattered Showers
In Union County, showers likely at times with highs near 84°F and lows around 65°F. Rainfall predicted to have a 74% chance with an estimated 0.05in. Wind will be moderate, blowing around 15mph on average and gusts of 23.3mph at 11 PM. The humidity will be on the higher side, averaging about 69%, the maximum being 90% at 7 AM and 45% being its lowest at 4 PM. Barometric pressure is its highest of 29.72inHg at 1 AM, a lowest point of 29.63inHg at 7 PM with an avg 29.67inHg.

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