Williamstown, PA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Williamstown, a borough in Dauphin County, Pennsylvania.
Today
85°F
Sunny
Sunny, with a high near 85. East wind around 3 mph.
7-day forecast for Williamstown
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 85°F | Sunny | 3 mph E | 0% |
| Tonight | 62°F | Mostly Cloudy | 3 mph SE | 5% |
| Wednesday | 83°F | Showers And Thunderstorms Likely | 5 mph SE | 61% |
| Wednesday Night | 67°F | Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 mph SE | 55% |
| Thursday | 88°F | Partly Sunny then Showers And Thunderstorms | 2 to 6 mph S | 79% |
| Thursday Night | 68°F | Showers And Thunderstorms | 1 to 5 mph S | 79% |
| Friday | 88°F | Showers And Thunderstorms Likely | 1 to 5 mph SW | 72% |
| Friday Night | 67°F | Showers And Thunderstorms Likely | 3 mph SW | 72% |
| Saturday | 86°F | Partly Sunny then Chance Showers And Thunderstorms | 1 to 6 mph W | 54% |
| Saturday Night | 66°F | Chance Showers And Thunderstorms | 3 mph W | 54% |
| Sunday | 88°F | Mostly Sunny | 2 to 6 mph W | 11% |
| Sunday Night | 68°F | Partly Cloudy | 3 mph SW | 11% |
| Monday | 89°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 2 to 8 mph W | 21% |
| Monday Night | 66°F | Slight Chance Showers And Thunderstorms | 6 mph W | 21% |
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
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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 Aug 4, 2026.