Portsmouth, NH Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Portsmouth, a city in Rockingham County, New Hampshire.
Today
86°F
Sunny
Sunny, with a high near 86. West wind 5 to 10 mph.
7-day forecast for Portsmouth
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 86°F | Sunny | 5 to 10 mph W | 0% |
| Tonight | 62°F | Mostly Clear | 0 to 5 mph SW | 0% |
| Wednesday | 85°F | Partly Sunny | 0 to 5 mph SW | 0% |
| Wednesday Night | 68°F | Partly Cloudy | 5 mph S | 6% |
| Thursday | 88°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 5 mph S | 27% |
| Thursday Night | 71°F | Slight Chance Showers And Thunderstorms then Partly Cloudy | 0 to 5 mph SW | 24% |
| Friday | 91°F | Sunny then Slight Chance Showers And Thunderstorms | 5 mph SW | 25% |
| Friday Night | 70°F | Chance Showers And Thunderstorms then Slight Chance Showers And Thunderstorms | 0 to 5 mph SW | 25% |
| Saturday | 87°F | Mostly Sunny then Chance Showers And Thunderstorms | 0 to 5 mph SW | 48% |
| Saturday Night | 69°F | Chance Showers And Thunderstorms then Partly Cloudy | 0 to 5 mph SW | 43% |
| Sunday | 89°F | Sunny | 0 to 5 mph SW | 10% |
| Sunday Night | 69°F | Mostly Clear | 5 mph SW | 10% |
| Monday | 90°F | Sunny | 5 to 10 mph SW | 13% |
| Monday Night | 68°F | Mostly Clear | 5 to 10 mph W | 14% |
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 Aug 4, 2026.