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Joliet, IL Weather by Month and Climate Averages
Monthly normals · Rain · Snow
Sunshine · Freeze dates · Records · Best time to visit
What is the weather like in Joliet, IL?
Joliet, IL gets 38.0 in of precipitation a year over about 122 rainy days, and about 16.9 in of snow a season. July is the warmest month (average high 84°F) and January the coldest (average low 17°F).
Humid continental climate
Joliet, IL has hot summers and cold winters. Daytime highs range from about 32°F in January to 84°F in July. July is usually the wettest month, and snow falls in winter. The most comfortable time to visit is typically May and September to October, when daytime highs sit near 70°F.
| Season | Months | Avg low | Avg high |
|---|---|---|---|
| Winter | Dec–Feb | 19° | 35° |
| Spring | Mar–May | 39° | 60° |
| Summer | Jun–Aug | 62° | 82° |
| Autumn | Sep–Nov | 44° | 63° |
How much rain does Joliet get?
Joliet gets 38.0 in of precipitation in an average year, spread over about 122 days with measurable rain. That is more rainy days than 79% of the US.
July is the wettest month, with 4.5 in. February is the driest, with 1.8 in. May has the most rainy days, about 12.
The longest dry spell in the last five years lasted 25 days, to September 22, 2024.
From September 2025 to August 2026 Joliet got 37.2 in of rain, against a normal of 38.0 in for those months. June 2026 had the most, with 8.3 in.
See where Joliet ranks: rainiest cities in the US, US cities with the most rainy days, rainiest cities in Illinois.
Does it snow in Joliet?
Yes. Joliet gets about 16.9 in of snow in an average season, measured at the reporting station.
The snowiest winter on record is 2013–14, with 55.7 in.
The most recent measurable snow at the station fell on March 24, 2006.
See where Joliet ranks: snowiest cities in the US.
Joliet weather by month
Joliet weather in January
In January, Joliet averages a high of 32°F and a low of 17°F. It gets 2.0 in of precipitation over about 11 rainy days. Estimated sunshine is 24% of daylight hours, derived from ERA5 cloud cover. The January record high is 65°F (1997) and the record low is -26°F (1985).
Joliet weather in February
In February, Joliet averages a high of 36°F and a low of 20°F. It gets 1.8 in of precipitation over about 9 rainy days. Estimated sunshine is 42% of daylight hours, derived from ERA5 cloud cover. The February record high is 73°F (2000) and the record low is -20°F (1979).
Joliet weather in March
In March, Joliet averages a high of 47°F and a low of 29°F. It gets 2.3 in of precipitation over about 10 rainy days. Estimated sunshine is 34% of daylight hours, derived from ERA5 cloud cover. The March record high is 86°F (1986) and the record low is -7°F (2002).
Joliet weather in April
In April, Joliet averages a high of 60°F and a low of 39°F. It gets 3.9 in of precipitation over about 12 rainy days. Estimated sunshine is 38% of daylight hours, derived from ERA5 cloud cover. The April record high is 92°F (1986) and the record low is 11°F (1982).
Joliet weather in May
In May, Joliet averages a high of 71°F and a low of 49°F. It gets 4.5 in of precipitation over about 12 rainy days. Estimated sunshine is 38% of daylight hours, derived from ERA5 cloud cover. The May record high is 95°F (2012) and the record low is 28°F (2020). May is one of the most comfortable months to visit.
Joliet weather in June
In June, Joliet averages a high of 81°F and a low of 60°F. It gets 4.3 in of precipitation over about 11 rainy days. Estimated sunshine is 50% of daylight hours, derived from ERA5 cloud cover. The June record high is 104°F (1988) and the record low is 35°F (1985).
Joliet weather in July
In July, Joliet averages a high of 84°F and a low of 64°F. It gets 4.5 in of precipitation over about 9 rainy days. Estimated sunshine is 48% of daylight hours, derived from ERA5 cloud cover. The July record high is 103°F (1995) and the record low is 47°F (2024).
Joliet weather in August
In August, Joliet averages a high of 82°F and a low of 63°F. It gets 4.0 in of precipitation over about 9 rainy days. Estimated sunshine is 52% of daylight hours, derived from ERA5 cloud cover. The August record high is 102°F (1988) and the record low is 39°F (1986).
Joliet weather in September
In September, Joliet averages a high of 77°F and a low of 55°F. It gets 3.2 in of precipitation over about 8 rainy days. Estimated sunshine is 53% of daylight hours, derived from ERA5 cloud cover. The September record high is 97°F (1978) and the record low is 32°F (1983). September is one of the most comfortable months to visit.
Joliet weather in October
In October, Joliet averages a high of 63°F and a low of 43°F. It gets 3.1 in of precipitation over about 9 rainy days. Estimated sunshine is 50% of daylight hours, derived from ERA5 cloud cover. The October record high is 88°F (2025) and the record low is 17°F (1976). October is one of the most comfortable months to visit.
Joliet weather in November
In November, Joliet averages a high of 49°F and a low of 32°F. It gets 2.5 in of precipitation over about 10 rainy days. Estimated sunshine is 45% of daylight hours, derived from ERA5 cloud cover. The November record high is 78°F (1978) and the record low is -2°F (1977).
Joliet weather in December
In December, Joliet averages a high of 37°F and a low of 22°F. It gets 1.9 in of precipitation over about 10 rainy days. Estimated sunshine is 31% of daylight hours, derived from ERA5 cloud cover. The December record high is 70°F (1982) and the record low is -20°F (1983).
Sunshine, humidity and wind in Joliet
September is the sunniest month in Joliet, with estimated sunshine of 53% of daylight hours from ERA5 cloud cover. January is the cloudiest, at 24%. The annual cloud-cover estimate is 42% of daylight hours; it is not a measurement of sunshine duration. Joliet is cloudier than 80% of the US.
Humidity peaks in January at 77% and is lowest in June at 59%.
Joliet has about 16 days a year above 90°F. Joliet is cooler than 67% of the US.
Thunderstorms occur on about 3 days a year.
See where Joliet ranks: sunniest cities in the US, cloudiest cities in the US, hottest cities in the US.
First and last freeze in Joliet
The first fall freeze in Joliet typically comes around October 19, and the last spring freeze around April 21. That leaves a frost-free growing season of about 181 days.
Joliet weather records
These records cover JOLIET BRANDON ROAD LOCK/DAM during 1970–2026. Earlier records or other stations in the city may differ.
The hottest temperature on record at the Joliet station is 104°F, on June 26, 1988. The coldest is -26°F, on January 20, 1985.
The wettest day in the available station history brought 13.6 in of precipitation, on July 18, 1996.
44 all-time records have been set at the station since 1970.
The annual mean temperature has changed by +0.5°F per decade since 1976.
The best time to visit Joliet
The most comfortable time to visit is typically May and September to October, when daytime highs sit near 70°F.
Winter (December–February) is cold, with average highs around 35°F and lows near 19°F. Snow is possible.
Spring (March–May) is mild, with average highs around 60°F and lows near 39°F.
Summer (June–August) is hot, with average highs around 82°F and lows near 62°F.
Autumn (September–November) is mild, with average highs around 63°F and lows near 44°F.
Monthly climate
| Month | Average low | Average high | Precip | Rain days | Humidity | Estimated sunshine | Record high | Record low |
|---|---|---|---|---|---|---|---|---|
| January | 17° | 32° | 2.0 in | 11 | 77% | 24% | 65° | -26° |
| February | 20° | 36° | 1.8 in | 9 | 68% | 42% | 73° | -20° |
| March | 29° | 47° | 2.3 in | 10 | 64% | 34% | 86° | -7° |
| April | 39° | 60° | 3.9 in | 12 | 60% | 38% | 92° | 11° |
| May | 49° | 71° | 4.5 in | 12 | 61% | 38% | 95° | 28° |
| June | 60° | 81° | 4.3 in | 11 | 59% | 50% | 104° | 35° |
| July | 64° | 84° | 4.5 in | 9 | 71% | 48% | 103° | 47° |
| August | 63° | 82° | 4.0 in | 9 | 71% | 52% | 102° | 39° |
| September | 55° | 77° | 3.2 in | 8 | 68% | 53% | 97° | 32° |
| October | 43° | 63° | 3.1 in | 9 | 65% | 50% | 88° | 17° |
| November | 32° | 49° | 2.5 in | 10 | 66% | 45% | 78° | -2° |
| December | 22° | 37° | 1.9 in | 10 | 72% | 31% | 70° | -20° |
Station: JOLIET BRANDON ROAD LOCK/DAM, 3 km from the city. Temperature normal baseline: 1991–2020, calculated from available NOAA GHCN-Daily observations. Available station history: 1970–2026; record values refer to this station and period, not the entire city’s history. Precipitation includes rain and the water equivalent of frozen precipitation; snowfall depth is shown separately when available. Sources and methods
From ERA5 reanalysis. Sunshine is estimated from cloud cover.
Joliet climate questions
How much rain does Joliet get?
Joliet gets 38.0 in of precipitation in an average year, over about 122 rainy days.
What is the wettest month in Joliet?
July is the wettest month in Joliet, with 4.5 in. February is the driest, with 1.8 in.
How many rainy days does Joliet have a year?
Joliet has about 122 days with measurable rain in an average year. May has the most, about 12.
Does it snow in Joliet?
Yes. Joliet gets about 16.9 in of snow in an average season. The snowiest winter on record is 2013–14, with 55.7 in.
What is the hottest month in Joliet?
July is the warmest month in Joliet, with an average high of 84°F.
What is the coldest month in Joliet?
January is the coldest month in Joliet, with an average low of 17°F.
What is the record high temperature in Joliet?
Within the available 1970–2026 station history, the record high at the Joliet station is 104°F, set on June 26, 1988. The record low is -26°F, on January 20, 1985.
What is the sunniest month in Joliet?
September is the sunniest month in Joliet, with estimated sunshine of 53% of daylight hours from ERA5 cloud cover. January is the cloudiest.
When is the first frost in Joliet?
The first fall freeze in Joliet typically comes around October 19. The last spring freeze is around April 21.
What is the best time to visit Joliet?
The most comfortable time to visit is typically May and September to October, when daytime highs sit near 70°F.