Joliet, Illinois Weather
Day 93 of summer. Read today’s microseason across nine climate regions →
Joliet weather forecast — hour by hour, 7-day outlook, NOAA radar
Conditions updated 12:50 AM CDT · Open-Meteo
- TodaySep 21Overcast28%—62°56°—
- TuesdaySep 22Overcast15%—61°52°-1°
- WednesdaySep 23Overcast——62°56°+1°
- ThursdaySep 24Overcast——67°59°+5°
- FridaySep 25Overcast——69°54°+2°
- SaturdaySep 26Overcast——60°55°-9°
- SundaySep 27Overcast——72°52°+12°
Air quality now AQI 39 · Good
AQI 39 (Good), driven by PM2.5. AQI flat over the last 6 hours (within ±3 points). PM2.5 at 6.0 µg/m³, PM10 at 6.1 µg/m³ — typical background levels with no transport signature.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
PM × Wind × Precip
PM2.5 at 6.0 µg/m³, PM10 at 6.1 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.98
- Wind
- breezy
- 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).
September dries up ditches or breaks down bridges.
- Moonrise
- 4:30 PM
- Moonset
- 1:08 AM
- In sign
- ♑︎ Capricorn
Joliet at a glance
- Today vs. normal: Today averages 59°F (high 62°F, low 56°F), 7°F below the 66°F normal for Sep 21
- Last frost: April 19 (1991–2020 median, NOAA station 4 km away)
- Microseason: Sep 21–25
- Planting calendar: September — plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, winter squash
15-Day Forecast — Joliet
- Mon62°56°28%
- Tue61°52°15%
- Wed62°56°2%
- Thu67°59°0%
- Fri69°54°0%
- Sat60°55°1%
- Sun72°52°6%
- Mon73°53°9%
- Tue68°55°26%
- Wed69°52°19%
- Thu71°51°17%
- Fri66°56°23%
- Sat65°59°23%
- Sun84°60°19%
- Mon75°56°13%
Forecast data from Open-Meteo (CC BY 4.0).
Live wind & temperature near Joliet
Interactive wind and temperature map centered on Joliet — it loads in your browser. Open the full weather map.
Right now in the garden
Fall planting + final harvests
As of September 21, the season's first frost (typically October 25) is approaching. Pick what frost-tender plants still carry before the next cold front. This city's planting calendar for September: plant garlic (overwinter); harvest tomatoes, peppers, beans, summer squash, and winter squash.
SPC Convective Outlook
Storm Prediction Center — Joliet
SPC includes Joliet in the general thunderstorm area tomorrow — no severe risk, but storms are possible.
- TODAYNONENo severe risk
- TOMORROWTSTMGeneral Thunderstorms
- DAY 3NONENo severe risk
Thunderstorms possible. Not severe, but capable of producing lightning and brief heavy rain.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook.
Sun & seasons in Joliet
Joliet sits in Will County, where the year’s longest day runs 15h 11m of daylight and its shortest just 9h 10m — a swing of +6h 1m between the June and December solstices. Clocks spring forward on Sunday, March 8, 2026 and fall back on Sunday, November 1, 2026.
Chicago, the state’s largest city, lies about 33 miles to the NE. The nearest town Joliet tracks is Naperville, roughly 16 miles to the N.
Air quality in Joliet
Air quality in Joliet’s county has trended cleaner since 2020; its cleanest year on record was 2024 (median AQI 44). See the full air-quality history for Joliet.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| March | lettuce, peas, spinach, radishes | — |
| April | lettuce, peas, spinach, radishes | radishes |
| May | tomatoes, peppers, beans, squash | lettuce, peas, spinach, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, spinach, radishes |
| July | tomatoes, peppers, beans, squash | lettuce, peas, beans, summer squash, garlic |
| August | beans, squash, fall brassicas, carrots | tomatoes, peppers, beans, summer squash, winter squash |
| September | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash |
| October | garlic (overwinter) | tomatoes, peppers, beans, summer squash, winter squash, fall brassicas, carrots |
| November | — | fall brassicas, carrots |
A year in weather
In Joliet, July runs warmest near 76°F and January coldest around 24°F, while May is the wettest month (4.4 inches) and January the driest (1.8 inches).
| Month | Mean temp | Precip |
|---|---|---|
| January | 24° | 1.8″ |
| February | 27° | 1.9″ |
| March | 38° | 3.0″ |
| April | 51° | 3.7″ |
| May | 60° | 4.4″ |
| June | 70° | 4.1″ |
| July | 76° | 2.9″ |
| August | 76° | 3.0″ |
| September | 68° | 3.0″ |
| October | 55° | 2.9″ |
| November | 40° | 3.2″ |
| December | 28° | 2.3″ |
Regional context
Similar climates Rockdale, IL, Shorewood, IL, Crystal Lawns, IL
By modelled 1991-2020 normals (EC_Earth3P_HR model via Open-Meteo), Joliet sees 24°F Januarys and 76°F Julys, a 53°F range, plus around 36.2 inches of precipitation.
Summer convection drives Joliet's precipitation: May logs 4.4 inches, against January's 1.8 inches — warm-season storms carry Joliet's moisture. That puts Joliet in a summer-convective cohort with places like Rockdale, IL, Shorewood, IL and Crystal Lawns, IL.
The cool-season window in Joliet starts at April 19, when nights stop freezing — think kale, peas, spinach, and parsnips. Hold Joliet's tender crops — tomatoes, peppers, basil — until 10-14 days past Joliet's last frost. Joliet's window closes around October 25 as Joliet's overnight lows return below freezing. Sheltered Joliet yards can escape a light frost.
Similar climates: Rockdale, IL, Shorewood, IL, Crystal Lawns, IL, Sunnyland, IL, Preston Heights, IL.
Frequently asked
- When does it freeze in Joliet?
- In Joliet, expect the last spring frost near April 19; Joliet's first autumn frost comes around October 25.
- What is the rainy season in Joliet?
- Rainfall in Joliet peaks in May near 4.4 inches, out of about 36 inches annually.
- What is the warmest month in Joliet?
- The warmest stretch in Joliet comes in July, around 76°F on average.
- What is the coldest month in Joliet?
- On average January is the chilliest month in Joliet, about 24°F.
- When can I start a vegetable garden in Joliet?
- Frost-hardy sowings begin at April 19 in Joliet; warm-season starts follow two weeks on.
- What hardiness zone is Joliet?
- Joliet sits in the USDA zone set by January lows near 24°F; the USDA ZIP tool gives the band.
- What is the 10-day forecast for Joliet?
- Joliet's extended outlook — daily high and low temperatures and precipitation chances for each upcoming day — is in the daily forecast above.
- Will it rain this week in Joliet?
- See this week's day-by-day rain chances for Joliet in the daily forecast above, and the next 24 hours in the hourly chart.
- What is the weather like right now in Joliet?
- Current conditions for Joliet and the next 24 hours — temperature, precipitation chance, and wind by the hour — are in the hourly forecast chart above.
- How often is the Joliet forecast updated?
- The Joliet forecast on this page is built from Open-Meteo weather-model data and refreshes regularly through the day.
- When are sunrise and sunset in Joliet?
- Today's sunrise and sunset times for Joliet are in the Almanac section above, along with civil dawn, civil dusk, and day length. Day length is longest near the summer solstice and shortest near the winter solstice.
- How accurate is the weather forecast for Joliet?
- The next few days in Joliet's forecast are the most reliable; accuracy declines beyond about a week as weather-model uncertainty grows.
Joliet sits at 41.5°N; its climate zone is warm-summer humid continental (Köppen approximation).
ZIP codes in Joliet
- 60421
- 60431
- 60432
- 60433
- 60434
- 60435
- 60436
- 60586