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 frost timing
Counties sorted by last spring frost.
Latest at top, earliest at bottom. In most states this matches the north-to-south gradient.
- Blaine CountySpring Jun 2·Fall Sep 23113-day season
- Elmore CountySpring May 30·Fall Sep 18111-day season
- Caribou CountySpring May 27·Fall Sep 12108-day season
- Bear Lake CountySpring May 25·Fall Sep 16114-day season
- Idaho CountySpring May 22·Fall Sep 7108-day season
- Teton CountySpring May 22·Fall Sep 20121-day season
- Bonneville CountySpring May 19·Fall Sep 23127-day season
- Cassia CountySpring May 17·Fall Sep 26132-day season
- Clearwater CountySpring May 17·Fall Sep 20126-day season
- Valley CountySpring May 16·Fall Sep 24131-day season
- Boise CountySpring May 15·Fall Sep 23131-day season
- Jefferson CountySpring May 14·Fall Sep 21130-day season
- Camas CountySpring May 11·Fall Sep 28140-day season
- Clark CountySpring May 10·Fall Oct 2145-day season
- Lincoln CountySpring May 8·Fall Oct 7152-day season
- Gem CountySpring May 7·Fall Sep 29145-day season
- Butte CountySpring May 6·Fall Oct 3150-day season
- Lewis CountySpring May 5·Fall Oct 2150-day season
- Bannock CountySpring May 4·Fall Oct 4153-day season
- Oneida CountySpring May 4·Fall Oct 2151-day season
- Fremont CountySpring May 3·Fall Oct 4154-day season
- Lemhi CountySpring May 2·Fall Oct 5156-day season
- Minidoka CountySpring May 2·Fall Oct 15166-day season
- Nez Perce CountySpring May 2·Fall Oct 9160-day season
- Custer CountySpring May 1·Fall Oct 7159-day season
- Franklin CountySpring Apr 30·Fall Oct 10163-day season
- Madison CountySpring Apr 30·Fall Oct 7160-day season
- Latah CountySpring Apr 28·Fall Oct 5160-day season
- Washington CountySpring Apr 28·Fall Oct 7162-day season
- Twin Falls CountySpring Apr 25·Fall Oct 15173-day season
- Shoshone CountySpring Apr 24·Fall Oct 14173-day season
- Jerome CountySpring Apr 23·Fall Oct 17177-day season
- Adams CountySpring Apr 22·Fall Oct 16177-day season
- Bingham CountySpring Apr 22·Fall Oct 16177-day season
- Bonner CountySpring Apr 21·Fall Oct 10172-day season
- Gooding CountySpring Apr 19·Fall Oct 15179-day season
- Power CountySpring Apr 19·Fall Oct 21185-day season
- Benewah CountySpring Apr 14·Fall Oct 19188-day season
- Boundary CountySpring Apr 10·Fall Oct 16189-day season
- Canyon CountySpring Apr 5·Fall Oct 30208-day season
- Ada CountySpring Apr 2·Fall Oct 31212-day season
- Kootenai CountySpring Apr 1·Fall Nov 1214-day season
- Payette CountySpring Mar 31·Fall Oct 31214-day season
- Owyhee CountySpring Mar 30·Fall Oct 31215-day season
Alphabetical
All Idaho counties — A to Z.
- Ada County
- Adams County
- Bannock County
- Bear Lake County
- Benewah County
- Bingham County
- Blaine County
- Boise County
- Bonner County
- Bonneville County
- Boundary County
- Butte County
- Camas County
- Canyon County
- Caribou County
- Cassia County
- Clark County
- Clearwater County
- Custer County
- Elmore County
- Franklin County
- Fremont County
- Gem County
- Gooding County
- Idaho County
- Jefferson County
- Jerome County
- Kootenai County
- Latah County
- Lemhi County
- Lewis County
- Lincoln County
- Madison County
- Minidoka County
- Nez Perce County
- Oneida County
- Owyhee County
- Payette County
- Power County
- Shoshone County
- Teton County
- Twin Falls County
- Valley County
- Washington County