O'Fallon, Illinois Weather
Cicadas claim the scorching afternoon. Day 14 of summer. Read this microseason across nine climate regions →
O'Fallon weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJul 4Light Drizzle29%—96°75°—
- SundayJul 5Light Drizzle20%0.02″84°73°-12°
- MondayJul 6Light Showers21%—87°69°+3°
- TuesdayJul 7Overcast13%—85°67°-2°
- WednesdayJul 8Overcast15%—89°66°+4°
- ThursdayJul 9Light Drizzle30%—94°71°+5°
- FridayJul 10Heavy Drizzle30%0.01″89°72°-5°
AQI 37 (Good), driven by Ozone. AQI flat over the last 6 hours (within ±4 points). Ozone at AQI 32 now. With UV 0.7 peaking around 1 PM under partly cloudy skies, surface ozone likely climbs to AQI 5 around 1 PM.
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 32 now. With UV 0.7 peaking around 1 PM under partly cloudy skies, surface ozone likely climbs to AQI 5 around 1 PM.
- Present
- AQI 32
- UV peak
- 0.7 at 1 PM
- Sky at peak
- partly cloudy
- Projected peak
- AQI 5
PM × Wind × Precip
PM2.5 at 5.4 µg/m³ (AQI 30) with a 0.92 fine-to-coarse ratio and 6 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.92
- 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).
If the first of July be rainy weather, 'twill rain more or less for four weeks together.
- Moonrise
- 10:52 PM
- Moonset
- 10:07 AM
- In sign
- ♓︎ Pisces
Cicadas claim the scorching afternoon
O'Fallon at a glance
- Today vs. normal: 6°F above the seasonal normal for this latitude
- Last frost: April 8 (climatological average for this latitude)
- Microseason: Jul 1–5
- Planting window: Harvest early potatoes. Begin drying onions on the surface.
ZIP code: 62269
16-Day Forecast — O'Fallon
- Sat96°75°29%
- Sun84°73°20%
- Mon87°69°21%
- Tue85°67°13%
- Wed89°66°15%
- Thu94°71°30%
- Fri89°72°30%
- Sat88°73°19%
- Sun78°62°11%
- Mon75°58°2%
- Tue78°60°7%
- Wed82°64°12%
- Thu82°66°14%
- Fri82°69°10%
- Sat86°69°13%
- Sun90°72°16%
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 — O'Fallon
SPC has placed O'Fallon in the Marginal Risk category for severe thunderstorms today.
- TODAYMRGLMarginal Risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3TSTMGeneral Thunderstorms
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 O'Fallon
- 62269