Union County, Illinois
Local growing conditions for Union County: the USDA hardiness zones found here, frost dates, and live weather for communities across the county. Based on 7 ZIP codes in our data.
Hardiness zones in Union County
Union County spans these USDA plant hardiness zones (by number of ZIP codes):
Local weather & frost dates
Open any community in Union County for its live forecast, frost dates, and planting calendar:
Alto Pass 62905
Anna 62906
Cobden 62920
Dongola 62926
Jonesboro 62952
Mill Creek 62961
Grand Tower 62998
More for Illinois
- Agriculture in Illinois
- Frost dates across Illinois
- USDA hardiness zones explained
- Planting calendar by ZIP code
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.