Portsmouth, NH Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Portsmouth, a city in Rockingham County, New Hampshire.
Tonight
48°F
Partly Cloudy
Partly cloudy, with a low around 48. South wind 0 to 5 mph.
7-day forecast for Portsmouth
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 48°F | Partly Cloudy | 0 to 5 mph S | 0% |
| Sunday | 61°F | Rain | 0 to 5 mph S | 90% |
| Sunday Night | 49°F | Rain | 5 mph NE | 83% |
| Monday | 67°F | Mostly Sunny | 5 to 10 mph NE | 1% |
| Monday Night | 48°F | Partly Cloudy | 0 to 5 mph NE | 0% |
| Tuesday | 63°F | Partly Sunny | 5 to 10 mph NE | 1% |
| Tuesday Night | 47°F | Partly Cloudy | 0 to 10 mph NE | 0% |
| Wednesday | 63°F | Mostly Sunny | 10 to 15 mph NE | 1% |
| Wednesday Night | 47°F | Partly Cloudy | 5 to 10 mph NE | 6% |
| Thursday | 63°F | Slight Chance Rain Showers | 10 to 15 mph NE | 19% |
| Thursday Night | 48°F | Chance Rain Showers | 5 to 15 mph NE | 31% |
| Friday | 63°F | Chance Rain Showers | 15 mph NE | 40% |
| Friday Night | 49°F | Chance Rain Showers | 10 to 15 mph NE | 41% |
| Saturday | 65°F | Chance Rain Showers | 15 to 20 mph NE | 40% |
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 Sep 20, 2026.