Williamstown, PA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Williamstown, a borough in Dauphin County, Pennsylvania.
Tonight
48°F
Mostly Clear
Mostly clear, with a low around 48. Southeast wind 2 to 6 mph.
7-day forecast for Williamstown
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 48°F | Mostly Clear | 2 to 6 mph SE | 0% |
| Wednesday | 73°F | Mostly Sunny | 2 to 8 mph S | 0% |
| Wednesday Night | 57°F | Mostly Cloudy then Rain Showers Likely | 7 mph S | 73% |
| Thursday | 72°F | Rain Showers | 3 to 8 mph S | 88% |
| Thursday Night | 56°F | Chance Rain Showers | 3 mph SW | 49% |
| Friday | 69°F | Chance Rain Showers | 2 mph NW | 49% |
| Friday Night | 46°F | Chance Rain Showers | 2 mph NW | 48% |
| Saturday | 63°F | Slight Chance Rain Showers | 3 to 7 mph NW | 17% |
| Saturday Night | 38°F | Partly Cloudy | 6 mph NW | 14% |
| Sunday | 59°F | Mostly Sunny | 7 mph W | 9% |
| Sunday Night | 36°F | Slight Chance Rain Showers | 7 mph W | 19% |
| Monday | 59°F | Slight Chance Rain Showers | 7 to 10 mph NW | 24% |
| Monday Night | 35°F | Slight Chance Rain Showers | 5 to 8 mph W | 21% |
| Tuesday | 62°F | Mostly Sunny | 7 to 10 mph W | 13% |
Forecast source: National Weather Service (api.weather.gov) for Williamstown (40.581, -76.617). Updated through the day.
Growing snapshot for Williamstown
Last spring frost
May 1
First fall frost
Oct 16
Growing season
168 days
Hardiness zone
6b
More local growing data for Williamstown: nearby ZIP 17098 weather · frost dates · planting calendar · Pennsylvania frost dates
Nearby towns & communities
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Middletown
Millersburg
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Paxtang
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West Fairview
Climate data from the nearest NOAA station, Dehart Dam, Pa (10.9 mi from Williamstown). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.