Union County, South Dakota

Local growing conditions for Union County: the USDA hardiness zones found here, frost dates, and live weather for communities across the county. Based on 4 ZIP codes in our data.

Hardiness zones in Union County

Union County spans these USDA plant hardiness zones (by number of ZIP codes):

Zone 5 (4)

Local weather & frost dates

Open any community in Union County for its live forecast, frost dates, and planting calendar:

Alcester 57001 Elk Point 57025 Jefferson 57038 North Sioux City 57049

More for South Dakota

Agriculture in South Dakota
Frost dates across South Dakota
USDA hardiness zones explained
Planting calendar by ZIP code

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County growing conditions are compiled from our ZIP-code database, USDA hardiness-zone data, and NOAA climate normals. Conditions vary within a county by elevation and local microclimate. Page updated Aug 4, 2026.