Frost dates · Idaho
Idaho frost dates, county by county.
Last spring frost and first fall frost probability data for all 44 counties in Idaho, 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 Idaho
64 days separate the earliest and latest counties.
The median last spring frost in Owyhee County is March 30 — 64 days earlier than Blaine County at June 2. Statewide averages aren't useful planting tools; pick your county below for the data that actually applies to your fields.
By geography
Idaho 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
44 counties · click any county for full frost data