Johnston City, Illinois Weather
Fireflies pulse through the magnolias. Day 77 of spring. Read this microseason across nine climate regions →
Johnston City weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast——84°59°—
- FridayJun 5Overcast——88°66°+4°
- SaturdayJun 6Drizzle17%—87°69°-1°
- SundayJun 7Heavy Showers51%0.60″76°71°-11°
- MondayJun 8Showers66%—85°70°+9°
- TuesdayJun 9Showers43%—90°71°+5°
- WednesdayJun 10Light Drizzle29%—89°73°-1°
Ozone at AQI 90 — peak already passed at 1 PM under partly cloudy skies. AQI up 21 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 90 — peak already passed at 1 PM under partly cloudy skies. Levels should ease through evening.
- Present
- AQI 90
- UV peak
- 4.6 at earlier today
- Sky at peak
- partly cloudy
- Projected peak
- AQI 90
PM × Wind × Precip
PM2.5 at 5.6 µg/m³, PM10 at 7.0 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.80
- 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
- 4:18 AM
- Moonset
- 2:04 PM
- In sign
- ♒︎ Aquarius
Fireflies pulse through the magnolias
Johnston City at a glance
- Today vs. normal: 7°F above the seasonal normal for this latitude
- Last frost: April 3 (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 — Johnston City
SPC has placed Johnston City 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.