Portsmouth, NH Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Portsmouth, a city in Rockingham County, New Hampshire.
Today
74°F
Mostly Sunny
Mostly sunny. High near 74, with temperatures falling to around 68 in the afternoon. Southwest wind around 5 mph.
7-day forecast for Portsmouth
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 74°F | Mostly Sunny | 5 mph SW | 3% |
| Tonight | 55°F | Partly Cloudy | 5 mph SW | 2% |
| Thursday | 73°F | Mostly Cloudy then Chance Light Rain | 5 to 10 mph SW | 35% |
| Thursday Night | 59°F | Mostly Cloudy then Chance Light Rain | 5 mph SW | 40% |
| Friday | 69°F | Light Rain | 0 to 5 mph S | 80% |
| Friday Night | 53°F | Light Rain | 0 to 5 mph E | 92% |
| Saturday | 63°F | Light Rain | 5 mph NE | 80% |
| Saturday Night | 43°F | Chance Light Rain | 5 mph N | 36% |
| Sunday | 58°F | Chance Light Rain | 5 to 10 mph W | 30% |
| Sunday Night | 36°F | Partly Cloudy | 5 mph W | 9% |
| Monday | 56°F | Mostly Sunny then Slight Chance Light Rain | 5 to 10 mph W | 17% |
| Monday Night | 34°F | Slight Chance Light Rain then Partly Cloudy | 5 mph W | 15% |
| Tuesday | 57°F | Mostly Sunny | 5 to 10 mph W | 9% |
| Tuesday Night | 33°F | Partly Cloudy | 5 to 10 mph W | 8% |
Forecast source: National Weather Service (api.weather.gov) for Portsmouth (43.061, -70.780). Updated through the day.
Growing snapshot for Portsmouth
Last spring frost
May 4
First fall frost
Oct 8
Growing season
157 days
Hardiness zone
6a
More local growing data for Portsmouth: nearby ZIP 03801 weather · frost dates · planting calendar · New Hampshire frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Greenland, Nh (3.9 mi from Portsmouth). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.