Joliet Climate by Month
Joliet, Illinois, United States
Warm summers and freezing winters, with rain spread through the year.
Joliet has warm summers and freezing winters, with rain spread through the year. July is the warmest month, with highs around 86°F (30°C); January is the coolest at 33°F (1°C), and nights dip to 17°F (-9°C). It gets 39 in (986 mm) of rain a year, spread across the months.
- Warmest month
- 86°F(30°C)
- Average high, July
- Coldest nights
- 17°F(-9°C)
- Average low, January
- Rain per year
- 39 in(986 mm)
- No clear rainy season
- Humidity
- 73%
- Sunniest: July
Best and worst months in Joliet
Best for weatherThe most comfortable weather comes in May and September, with highs around 76°F (24°C) and about 4.0 in (102 mm) of rain a month.
Least pleasantJanuary is the least pleasant month: it's the coldest, with highs of only 33°F (1°C).
Comfort combines how close the afternoon high is to 75°F (24°C) with how much rain falls and how humid it is. See where the weather is best in September.
Temperature and rain through the year
Highs and lows (°F)
Average highAverage low
Rain (in per month)
Joliet weather by month
| Month | High | Low | Rain | Humidity | Sun |
|---|---|---|---|---|---|
| JanJanuary | 33°F(1°C) | 17°F(-9°C) | 1.7 in(43 mm) | 88% | 1.4 |
| FebFebruary | 38°F(3°C) | 20°F(-7°C) | 1.6 in(40 mm) | 75% | 2.5 |
| MarMarch | 49°F(10°C) | 30°F(-1°C) | 2.4 in(61 mm) | 72% | 3.6 |
| AprApril | 62°F(17°C) | 40°F(4°C) | 4.5 in(114 mm) | 63% | 4.5 |
| MayMayBest | 73°F(23°C) | 50°F(10°C) | 4.5 in(115 mm) | 64% | 5.1 |
| JunJune | 82°F(28°C) | 60°F(16°C) | 4.8 in(122 mm) | 69% | 5.8 |
| JulJuly | 86°F(30°C) | 64°F(18°C) | 4.1 in(104 mm) | 71% | 5.9 |
| AugAugust | 84°F(29°C) | 63°F(17°C) | 4.1 in(103 mm) | 72% | 5.1 |
| SepSeptemberBest | 78°F(26°C) | 55°F(13°C) | 3.5 in(89 mm) | 68% | 4.4 |
| OctOctober | 65°F(18°C) | 43°F(6°C) | 2.9 in(74 mm) | 70% | 2.8 |
| NovNovember | 50°F(10°C) | 32°F(0°C) | 2.6 in(65 mm) | 80% | 1.7 |
| DecDecember | 38°F(3°C) | 22°F(-5°C) | 2.2 in(56 mm) | 89% | 1.3 |
1991–2020 averages. Sun is solar radiation in kWh/m² per day. Highlighted: the most comfortable months.
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