DeKalb, Illinois Weather
Fireflies rise from the lawn. Day 76 of spring. Read this microseason across nine climate regions →
DeKalb weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast——81°49°—
- ThursdayJun 4Overcast——86°58°+5°
- FridayJun 5Light Showers76%0.30″77°67°-9°
- SaturdayJun 6Showers67%0.01″82°63°+5°
- SundayJun 7Overcast21%—79°60°-3°
- MondayJun 8Light Drizzle24%—80°64°+1°
- TuesdayJun 9Light Drizzle23%0.02″78°68°-2°
Ozone at AQI 55 — peak already passed at 1 PM under clear skies. AQI up 18 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 55 — peak already passed at 1 PM under clear skies. Levels should ease through evening.
- Present
- AQI 55
- UV peak
- 0.8 at earlier today
- Sky at peak
- clear
- Projected peak
- AQI 55
PM × Wind × Precip
PM2.5 at 8.1 µg/m³ (AQI 45) with a 0.77 fine-to-coarse ratio and 5 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.77
- 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).
The higher the clouds, the finer the weather.
- Moonrise
- 3:54 AM
- Moonset
- 12:46 PM
- In sign
- ♑︎ Capricorn
Fireflies rise from the lawn
DeKalb at a glance
- Today vs. normal: 8°F above the seasonal normal for this latitude
- Last frost: April 28 (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 — DeKalb
SPC has placed DeKalb in the Marginal Risk category for severe thunderstorms day after tomorrow.
- TODAYNONENo severe risk
- TOMORROWNONENo severe risk
- DAY 3MRGLMarginal 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.