Frost dates · New Hampshire
New Hampshire frost dates,
county by county.
Last spring frost and first fall frost probability data for all 10 counties in New Hampshire, 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 New Hampshire
30 days separate the earliest and latest counties.
The median last spring frost in Strafford County is April 17 — 30 days earlier than Coos County at May 17. 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.
- Coos CountySpring May 17·Fall Sep 30136-day season
- Carroll CountySpring May 4·Fall Oct 4153-day season
- Cheshire CountySpring May 2·Fall Oct 10161-day season
- Sullivan CountySpring May 1·Fall Oct 11163-day season
- Grafton CountySpring Apr 30·Fall Oct 20173-day season
- Merrimack CountySpring Apr 30·Fall Oct 9162-day season
- Rockingham CountySpring Apr 24·Fall Oct 15174-day season
- Hillsborough CountySpring Apr 20·Fall Oct 16179-day season
- Belknap CountySpring Apr 17·Fall Nov 1198-day season
- Strafford CountySpring Apr 17·Fall Oct 23189-day season
Alphabetical