Frost dates · Montana
Montana frost dates, county by county.
Last spring frost and first fall frost probability data for all 56 counties in Montana, 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 Montana
36 days separate the earliest and latest counties.
The median last spring frost in Dawson County is April 24 — 36 days earlier than Beaverhead County at May 30. Statewide averages aren't useful planting tools; pick your county below for the data that actually applies to your fields.
By geography
Montana 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
56 counties · click any county for full frost data