Williamstown, Pennsylvania Weather
Fireflies rise from the lawn. Day 76 of spring. Read this microseason across nine climate regions →
Williamstown weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Clear——78°51°—
- ThursdayJun 4Overcast——83°63°+5°
- FridayJun 5Overcast——83°63°0°
- SaturdayJun 6Heavy Drizzle37%—86°63°+3°
- SundayJun 7Light Showers47%0.09″79°62°-7°
- MondayJun 8Overcast21%—73°54°-6°
- TuesdayJun 9Partly Cloudy12%—77°49°+4°
Ozone at AQI 500 — peak already passed at 1 PM under clear skies. AQI up 15 in the last 6 hours — air quality is degrading. Levels should ease through evening.
AVOID OUTDOORS Avoid outdoor exertion. Keep windows closed; use HEPA filtration indoors if available.
What's driving it
Ozone × UV × Sky
Ozone at AQI 500 — peak already passed at 1 PM under clear skies. Levels should ease through evening.
- Present
- AQI 500
- UV peak
- 5.7 at earlier today
- Sky at peak
- clear
- Projected peak
- AQI 500
PM × Wind × Precip
PM2.5 at 5.0 µg/m³ (AQI 28) with a 0.76 fine-to-coarse ratio and 6 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.76
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
The higher the clouds, the finer the weather.
- Moonrise
- 2:58 AM
- Moonset
- 12:01 PM
- In sign
- ♑︎ Capricorn
Fireflies rise from the lawn
Williamstown at a glance
- Today vs. normal: 4°F above the seasonal normal for this latitude
- Last frost: April 19 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 3, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.