St. Charles, Illinois Weather
Cicadas claim the afternoon. Day 14 of summer. Read this microseason across nine climate regions →
St. Charles weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 4Light Rain84%0.22″82°70°—
- SundayJul 5Overcast19%—79°65°-3°
- MondayJul 6Overcast——80°62°+1°
- TuesdayJul 7Overcast——81°58°+1°
- WednesdayJul 8Overcast12%—81°61°0°
- ThursdayJul 9Light Showers53%0.18″77°65°-4°
- FridayJul 10Overcast46%—81°62°+4°
AQI 32 (Good), driven by Ozone. AQI flat over the last 6 hours (within ±3 points). Ozone at AQI 33. Overcast through the UV peak window (cloud cover ~65%) — afternoon ozone should stay flat.
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 33. Overcast through the UV peak window (cloud cover ~65%) — afternoon ozone should stay flat.
- Present
- AQI 33
- UV peak
- 2.1 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 5
PM × Wind × Precip
PM2.5 at 5.0 µg/m³ (AQI 28) with a 0.89 fine-to-coarse ratio and 2 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.89
- Wind
- calm
- 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).
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
- Moonrise
- 10:51 PM
- Moonset
- 9:57 AM
- In sign
- ♓︎ Pisces
Cicadas claim the afternoon
St. Charles at a glance
- Today vs. normal: 7°F above the seasonal normal for this latitude
- Last frost: April 28 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
16-Day Forecast — St. Charles
- Sat82°70°84%
- Sun79°65°19%
- Mon80°62°2%
- Tue81°58°1%
- Wed81°61°12%
- Thu77°65°53%
- Fri81°62°46%
- Sat81°61°15%
- Sun67°58°7%
- Mon74°55°7%
- Tue79°60°7%
- Wed79°62°26%
- Thu83°65°19%
- Fri83°69°26%
- Sat86°70°21%
- Sun83°70°32%
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 — St. Charles
SPC has placed St. Charles 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 St. Charles
- 60175
- 60174