Frost dates in New Hampshire
Across New Hampshire, the typical last spring frost is around May 7 and the first fall frost around Oct 4. Your own dates depend on where you are in the state; find your county below.
Most of the state's last spring frosts fall between Apr 30 and May 19, and its first fall frosts between Sep 26 and Oct 12.
These are the dates with a 50% chance of a 32°F frost on or after (spring) or on or before (fall), so plan tender crops a week or two after the spring date and keep row cover handy. For dates at your exact ZIP code, use the zone and frost date lookup; for what to plant when, see the planting guide by frost date.
Hardiness zones in New Hampshire: zone 4a, zone 4b, zone 5a, zone 5b, zone 6a, zone 6b
Frost dates by county in New Hampshire
| County | Last spring frost | First fall frost | Growing season |
|---|---|---|---|
| Belknap | Apr 30 | Oct 18 | About 171 days |
| Carroll | May 15 | Oct 1 | About 139 days |
| Cheshire | May 14 | Oct 1 | About 140 days |
| Coos | May 23 | Sep 26 | About 126 days |
| Grafton | May 15 | Sep 28 | About 136 days |
| Hillsborough | May 2 | Oct 8 | About 159 days |
| Merrimack | May 8 | Oct 3 | About 148 days |
| Rockingham | May 4 | Oct 8 | About 157 days |
| Strafford | May 3 | Oct 9 | About 159 days |
| Sullivan | May 14 | Oct 1 | About 140 days |
Source: NOAA NCEI U.S. Climate Normals 1991–2020, 50% probability of 32°F, from the weather station nearest each ZIP code; each county shows the middle value across its ZIP codes. Hills, valleys and cities can run a week or more earlier or later.