Frost dates · Iowa
Iowa frost dates, county by county.
Last spring frost and first fall frost probability data for all 99 counties in Iowa, computed from the NOAA 1991–2020 Climate Normals. Every county page surfaces the full probability table at three temperature thresholds plus crop-specific planting guidance.
Variation across Iowa
29 days separate the earliest and latest counties.
The median last spring frost in Des Moines County is March 31 — 29 days earlier than Howard County at April 29. Statewide averages aren't useful planting tools; pick your county below for the data that actually applies to your fields.
By geography
Iowa counties on the map.
Each polygon is a county. Click for full frost-date detail. Color shows last-spring-frost timing — sage = earliest, amber = latest.
MapList
Last spring frostEarliestMedianLatest
99 counties · click any county for full frost data