Princeton, Illinois Weather
Cicadas claim the afternoon. Day 14 of summer. Read this microseason across nine climate regions →
Princeton weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 4Showers68%0.18″83°69°—
- SundayJul 5Foggy24%—83°67°0°
- MondayJul 6Overcast——81°64°-2°
- TuesdayJul 7Overcast——80°58°-1°
- WednesdayJul 8Overcast12%—82°63°+2°
- ThursdayJul 9Drizzle46%—79°66°-3°
- FridayJul 10Overcast32%—79°63°0°
AQI 23 (Good), driven by PM2.5. AQI projected to climb to 41 over the next 6 hours. PM scrubbed by 2 hours of recent rain — PM2.5 down to 6.6 µg/m³, PM10 to 7.5 µg/m³.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 10 PM.
What's driving it
Ozone × UV × Sky
Ozone at AQI 34. Overcast through the UV peak window (cloud cover ~70%) — afternoon ozone should stay flat.
- Present
- AQI 34
- UV peak
- 4.2 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 10
PM × Wind × Precip
PM scrubbed by 2 hours of recent rain — PM2.5 down to 6.6 µg/m³, PM10 to 7.5 µg/m³.
- PM2.5/PM10
- 0.88
- Wind
- light
- Recent rain
- 2h in last 6h
- Pattern
- washed out
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).
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
- Moonrise
- 10:54 PM
- Moonset
- 10:02 AM
- In sign
- ♓︎ Pisces
Cicadas claim the afternoon
Princeton at a glance
- Today vs. normal: 10°F above the seasonal normal for this latitude
- Last frost: April 24 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
ZIP code: 61356
16-Day Forecast — Princeton
- Sat83°69°68%
- Sun83°67°24%
- Mon81°64°4%
- Tue80°58°1%
- Wed82°63°12%
- Thu79°66°46%
- Fri79°63°32%
- Sat82°65°14%
- Sun67°58°10%
- Mon72°56°8%
- Tue76°60°9%
- Wed78°62°29%
- Thu82°65°18%
- Fri82°68°29%
- Sat85°70°23%
- Sun84°71°39%
Forecast data from Open-Meteo (CC BY 4.0).
Right now in the garden
Peak growing season
As of July 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.
SPC Convective Outlook
Storm Prediction Center — Princeton
SPC has placed Princeton in the Marginal Risk category for severe thunderstorms today.
- TODAYMRGLMarginal Risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3NONENo severe risk
Isolated severe storms possible. Limited threat for hail or damaging wind.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.
ZIP codes in Princeton
- 61356