Warm
Average highs sit around 29°C, giving warm days by monthly-average standards.
Weather Guide
Joliet, Illinois, United States Average Monthly Weather
Weather score42Mixed annual avg
Best months: July, August, June
Across the year, average daytime temperatures are around 15°C, sunshine averages 6.8h per day, and rainfall totals about 926mm. Sea temperatures average 11°C across the year.
Annual weather
Annual averages
Temp
15°C
Rain
926mm
Annual total
Sun
6.8h
Sea
11°C
Weather score
42
Mixed avg
Seasonal climate calendar
TemperatureTemp
RainRain
SunSun
SwimSwim
Weather scoreWeather score
Trip feel
Showers
Rainfall averages 103mm, so some wet days are possible.
Bright
Sunshine averages 10h per day, so bright days are a strong part of the month.
Cool sea
Sea temperatures average 21°C, so the water can feel cool.
Map
Weather map
Compare Joliet, Illinois, United States with nearby places by weather score, rain, sun, temperature, and swim conditions.
Temperature
July29°C average high
July is one of Joliet's warmest months, with daytime heat above the yearly average.
Warmest monthsMay to September
This stretch sets the upper range for average daytime heat.
Rain
July103mm average rain
July is one of Joliet's wettest months, so rain is likely to be a major planning factor.
Driest monthsJanuary to February, October, and December
This is the drier part of the year, when outdoor plans usually need less weather flexibility.
Sun
July10 hours average sun
July is one of Joliet's sunniest months, with some of the strongest bright-day conditions in the yearly averages.
Brightest monthsMay to August
This stretch has the strongest sunshine in the monthly averages.
Sea temperature
July21°C average sea
July is one of Joliet's warmest sea months, when swimming comfort is usually strongest.
Warmest seaJuly to September
Sea temperatures are usually near 21°C in this stretch, so swimming comfort is at its strongest.
Weather score
July76 weather score
July is one of Joliet's best weather-score months, combining the strongest overall balance in the yearly averages.
Best weather monthsJune to August
These months have the strongest weather score in the monthly averages.
