Decatur, Illinois Weather
Fireflies pulse through the magnolias. Day 76 of spring. Read this microseason across nine climate regions →
Decatur weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast——82°53°—
- ThursdayJun 4Overcast——85°58°+3°
- FridayJun 5Overcast35%—81°68°-4°
- SaturdayJun 6Light Showers53%—82°65°+1°
- SundayJun 7Light Showers31%—84°69°+2°
- MondayJun 8Drizzle44%—76°70°-8°
- TuesdayJun 9Drizzle27%—75°70°-1°
Ozone at AQI 73 — peak already passed at 1 PM under partly cloudy skies. AQI up 22 in the last 6 hours — air quality is degrading. Levels should ease through evening.
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 73 — peak already passed at 1 PM under partly cloudy skies. Levels should ease through evening.
- Present
- AQI 73
- UV peak
- 2.0 at earlier today
- Sky at peak
- partly cloudy
- Projected peak
- AQI 73
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
- 3:47 AM
- Moonset
- 12:55 PM
- In sign
- ♑︎ Capricorn
Fireflies pulse through the magnolias
Decatur at a glance
- Today vs. normal: 6°F above the seasonal normal for this latitude
- Last frost: April 15 (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.
SPC Convective Outlook
Storm Prediction Center — Decatur
SPC has placed Decatur in the General Thunderstorms category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWNONENo severe risk
- DAY 3TSTMGeneral Thunderstorms
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
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.