Last frost date in Portsmouth, New Hampshire
May 4
Average last frost in spring. In an early year (1 in 10) it's over by April 23; in a late year (1 in 10) it comes after May 18.
October 8
Average first frost in fall. 1 year in 10 it comes by September 27.
Source: NOAA U.S. Climate Normals 1991–2020, station Greenland (USC00273626), 3.6 miles from Portsmouth, elevation 95 ft. NOAA National Centers for Environmental Information. These are long-term averages, not a forecast.
| Early year | Average | Late year | |
|---|---|---|---|
| Last frost in spring | Apr 23 | May 4 | May 18 |
| First frost in fall | Sept 27 | Oct 8 | Oct 24 |
Frost-free days in an average year: 157
| Chance in a year | Average last in spring | Average first in fall | |
|---|---|---|---|
| Light frost (36°F) | Every year | May 16 | Sept 30 |
| Frost (32°F) | Every year | May 4 | Oct 8 |
| Hard freeze (28°F) | Every year | Apr 23 | Oct 21 |
Nights at 32°F or colder in an average year: 143
What to plant now in Portsmouth
- Spring planting calendar for an average last frost around April 30 Portsmouth: May 4
- Fall planting calendar for an average first frost around October 10 Portsmouth: October 8
Planting dates: USDA Home and Garden Bulletin No. 9 (1967), “Suburban and Farm Vegetable Gardens,” tables 4 and 5. How we match the table.
Nearby in New Hampshire
- Dover 10 mi · last frost May 3
- Rochester 19 mi · last frost Apr 30
- Manchester 34 mi · last frost Apr 30
- Concord 41 mi · last frost May 8
- Nashua 42 mi · last frost Apr 29
Updated