St. Joseph, Illinois Weather
Fireflies pulse through the magnolias. Day 77 of spring. Read this microseason across nine climate regions →
St. Joseph weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Overcast——83°51°—
- ThursdayJun 4Overcast——85°57°+2°
- FridayJun 5Heavy Rain26%0.41″85°66°0°
- SaturdayJun 6Light Showers63%—85°64°0°
- SundayJun 7Showers42%—85°69°0°
- MondayJun 8Showers43%0.04″82°70°-3°
- TuesdayJun 9Light Drizzle28%—84°70°+2°
Ozone at AQI 39 now. AQI flat over the last 6 hours (within ±3 points). With UV 0.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 9 by mid-afternoon.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 6 AM.
What's driving it
Ozone × UV × Sky
Ozone at AQI 39 now. With UV 0.0 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 9 by mid-afternoon.
- Present
- AQI 39
- UV peak
- 0.0 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 9
PM × Wind × Precip
PM2.5 at 5.3 µg/m³, PM10 at 5.8 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.91
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- background
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).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 4:21 AM
- Moonset
- 1:54 PM
- In sign
- ♑︎ Capricorn
Fireflies pulse through the magnolias
St. Joseph at a glance
- Today vs. normal: 11°F below the seasonal normal for this latitude
- Last frost: April 17 (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 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. Joseph
SPC has placed St. Joseph 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.