Alton, NH Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Alton, a community in Belknap County, New Hampshire.
Tonight
45°F
Partly Cloudy
Partly cloudy, with a low around 45. South wind around 0 mph.
7-day forecast for Alton
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 45°F | Partly Cloudy | 0 mph | 0% |
| Sunday | 56°F | Rain | 0 to 5 mph SE | 91% |
| Sunday Night | 47°F | Rain | 0 to 5 mph NE | 77% |
| Monday | 66°F | Mostly Sunny | 5 mph N | 0% |
| Monday Night | 42°F | Mostly Cloudy | 5 mph NE | 0% |
| Tuesday | 62°F | Mostly Sunny | 5 mph NE | 0% |
| Tuesday Night | 43°F | Partly Cloudy | 0 to 5 mph NE | 0% |
| Wednesday | 62°F | Mostly Sunny | 5 to 10 mph NE | 1% |
| Wednesday Night | 42°F | Partly Cloudy | 0 to 5 mph NE | 2% |
| Thursday | 62°F | Slight Chance Rain Showers | 5 to 10 mph NE | 16% |
| Thursday Night | 45°F | Chance Rain Showers | 0 to 10 mph NE | 30% |
| Friday | 61°F | Chance Rain Showers | 10 to 15 mph NE | 33% |
| Friday Night | 48°F | Chance Rain Showers | 10 to 15 mph NE | 39% |
| Saturday | 63°F | Chance Rain Showers | 10 to 15 mph N | 38% |
Forecast source: National Weather Service (api.weather.gov) for Alton (43.456, -71.222). Updated through the day.
Growing snapshot for Alton
Last spring frost
Apr 30
First fall frost
Oct 18
Growing season
170 days
Hardiness zone
5b
More local growing data for Alton: nearby ZIP 03809 weather · frost dates · planting calendar · New Hampshire frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Lakeport 2, Nh (14.5 mi from Alton). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 20, 2026.