Williamstown, PA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Williamstown, a borough in Dauphin County, Pennsylvania.
Today
73°F
Partly Sunny
Partly sunny, with a high near 73. East wind around 3 mph.
7-day forecast for Williamstown
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 73°F | Partly Sunny | 3 mph E | 2% |
| Tonight | 55°F | Rain Showers | 3 to 10 mph SE | 79% |
| Sunday | 72°F | Rain Showers | 5 to 10 mph S | 97% |
| Sunday Night | 50°F | Showers And Thunderstorms | 5 to 9 mph W | 91% |
| Monday | 69°F | Mostly Cloudy | 5 to 8 mph N | 14% |
| Monday Night | 45°F | Chance Rain Showers | 5 to 8 mph NE | 44% |
| Tuesday | 61°F | Chance Rain Showers | 8 mph E | 46% |
| Tuesday Night | 45°F | Chance Rain Showers | 7 to 12 mph E | 40% |
| Wednesday | 60°F | Chance Rain Showers | 8 to 12 mph E | 40% |
| Wednesday Night | 44°F | Chance Rain Showers | 7 to 12 mph E | 34% |
| Thursday | 62°F | Chance Rain Showers | 6 to 10 mph NE | 35% |
| Thursday Night | 44°F | Chance Rain Showers | 6 mph NE | 34% |
| Friday | 67°F | Slight Chance Rain Showers | 7 mph N | 24% |
| Friday Night | 44°F | Slight Chance Rain Showers | 7 mph N | 24% |
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 Sep 19, 2026.