Portsmouth, NH Weather & Growing Conditions
Tonight
49°F
Mostly Cloudy
Mostly cloudy, with a low around 49. South wind 0 to 5 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 49°F | Mostly Cloudy | 0 to 5 mph S | 6% |
| Wednesday | 75°F | Mostly Sunny | 5 mph SW | 6% |
| Wednesday Night | 55°F | Partly Cloudy | 5 mph SW | 3% |
| Thursday | 73°F | Mostly Cloudy then Isolated Rain Showers | 5 to 10 mph SW | 24% |
| Thursday Night | 60°F | Mostly Cloudy then Scattered Rain Showers | 5 mph SW | 42% |
| Friday | 69°F | Light Rain | 5 mph S | 81% |
| Friday Night | 54°F | Light Rain | 5 mph E | 85% |
| Saturday | 62°F | Light Rain | 5 mph N | 75% |
| Saturday Night | 43°F | Light Rain Likely | 5 mph NW | 55% |
| Sunday | 60°F | Chance Light Rain | 5 to 10 mph W | 29% |
| Sunday Night | 37°F | Partly Cloudy | 5 mph W | 13% |
| Monday | 57°F | Slight Chance Light Rain | 5 to 10 mph W | 20% |
| Monday Night | 35°F | Slight Chance Light Rain | 5 mph W | 19% |
| Tuesday | 57°F | Mostly Sunny then Slight Chance Light Rain | 5 to 15 mph W | 15% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Portsmouth, NH
Last spring frost
May 4
First fall frost
Oct 8
Growing season
157 days
Hardiness zone
6a
Explore more for Portsmouth, NH: full frost dates · planting calendar · New Hampshire frost dates
Climate data from the nearest NOAA station, Greenland, Nh (1.6 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.