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Union County Climate

Union County, South Dakota

NOAA NCEI 1991-2020 Climate Normals
JanFebMarAprMayJunJulAugSepOctNovDec46.9°AVG °F

Avg Annual Temp

46.9°F

Annual Precip

29.7"

Annual Snowfall

33.8"

Extreme Heat Days

17

days >= 90°F/yr

Monthly Temperature

54.4°F avgJFMAMJJASOND

Precipitation Calendar

Dry
Wet❄= snowfall
❄0.8"
❄0.8"
❄1.7"
❄3.2"
❄4.3"
4.6"
3.0"
3.6"
3.0"
❄2.5"
❄1.2"
❄1.0"
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Growing Season & Gardening

USDA Hardiness Zone

5a

Minimum winter temperature range for plant survival

Seasonal Overview

Comfort ZoneSpring35°59°9.2"Summer70°73°11.3"Fall35°63°6.7"Winter17°22°2.5"20°40°60°80°100°

National Comparison

Warmer than 19% of US counties
Wetter than 26% of US counties
More seasonal variation than 93% of US counties

7-Day Outlook

Forecast

Current Conditions

Air Quality

Safety

Weather Alerts

Climate Advisory: Union County

Climate Verdict

Union County has a cool, averaging 46.9°F annually, moderate rainfall of 29.7 inches per year, rare extreme heat with only 17.2 days above 90°F annually, moderate snowfall of 33.8 inches annually. This climate profile shapes everything from energy costs to outdoor recreation opportunities.

Seasonal Breakdown

Winters are very cold — January averages 17.3°F. summers are warm — July averages 73.1°F. Residents experience a substantial 56°F difference between winter and summer.

Outdoor & Gardening Guidance

Growing season and gardening data is currently limited for Union County. Check the USDA Plant Hardiness Zone Map and local extension office for specific guidance.

Regional Context

Union County closely matches the South Dakota statewide average temperature of 45.6°F, it is also noticeably wetter, receiving 6.9 inches more precipitation than the state average.

Frequently Asked Questions

What is the average temperature in Union County?
The average annual temperature in Union County, SD is 46.9°F, based on NOAA 30-year climate normals (1991-2020).
How much rain does Union County get?
Union County receives an average of 29.7 inches of precipitation per year, including both rain and meltwater from snow. This is based on NOAA 30-year climate normals.
Does it snow in Union County?
Yes, Union County receives an average of 33.8 inches of snowfall per year according to NOAA climate normals.
How hot does Union County get in summer?
The average summer temperature (June-August) in Union County is 71.1°F. The county experiences an average of 17 days per year above 90°F.
How cold are winters in Union County?
The average winter temperature (December-February) in Union County is 20.5°F. January, typically the coldest month, averages 17.3°F.

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Data sources: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. Forecast and alert data from National Weather Service API. Air quality data from Open-Meteo.

Climate normals are 30-year averages of weather variables. Station data is aggregated to county level. Forecasts and alerts are fetched live and may change frequently. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.

By Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor
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