Onset, Massachusetts Weather
Fireflies rise from the lawn. Day 77 of spring. Read this microseason across nine climate regions →
Onset weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——74°56°—
- FridayJun 5Overcast——75°57°+1°
- SaturdayJun 6Overcast20%—81°61°+6°
- SundayJun 7Showers69%0.11″79°55°-2°
- MondayJun 8Overcast20%—68°53°-11°
- TuesdayJun 9Overcast10%—67°52°-1°
- WednesdayJun 10Overcast——65°53°-2°
Ozone at AQI 46 now. AQI down 16 over the last 6 hours — air quality is improving sharply. With UV 3.3 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 20 by mid-afternoon.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 46 now. With UV 3.3 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 20 by mid-afternoon.
- Present
- AQI 46
- UV peak
- 3.3 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 20
PM × Wind × Precip
PM2.5 at 6.9 µg/m³ (AQI 38) with a 0.70 fine-to-coarse ratio and 6 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.70
- 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).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 3:16 AM
- Moonset
- 12:35 PM
- In sign
- ♑︎ Capricorn
Fireflies rise from the lawn
Onset at a glance
- Today vs. normal: 17°F below the seasonal normal for this latitude
- Last frost: April 26 (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 4, 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.