Climate of Illinois
The state Illinois has a continental climate. It is warm in the summer and cold in the winter. The average annual temperature for Illinois is 15° degrees and there is about 337 mm of rain in a year. It is dry for 207 days a year with an average humidity of 78% and an UV-index of 4.
Climate averages for the whole year
- Day: the average daily temperature during the day is between -1°C and 28°C
- Night:the average nighttime temperature is between -8°C and 18°C
- Rain: it rains 118 days and there is a total of approximately 336 mm rainfall
- Snow: it snows an average of 26 days per year
- Sun hours: throughout the year there are 2685 sun hours
Maximum temperature: | between -1°C and 28°C |
Warmest month: | 28°C in July |
Coldest month: | -1°C in January |
Night temperature: | between -8°C and 18°C |
Dry days: | 221 days |
Days with rain: | 118 days |
Days with snow: | 26 days |
Total rain sum: | 336 mm |
Hours of sunshine: | 2685 hours |
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Temperature graph
This graph shows the average maximum temperature (red) and minimum temperature (blue) for Illinois.
Precipitation graph
This graph shows the average amount of rainfall per month for Illinois.
Climate table of Illinois
In this climate table you can see at a glance what the average weather per month is for Illinois. The data has been collected over a 30-year period, from which an average per month has been derived. From year to year the differences may be larger or smaller, but with this climate table you have a good idea of what the weather for Illinois might be like in a given month.
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Day temp. (°C) | -1 | 2 | 9 | 16 | 22 | 27 | 28 | 27 | 25 | 17 | 9 | 2 |
Night temp. (°C) | -8 | -5 | 1 | 7 | 13 | 17 | 18 | 17 | 14 | 8 | 2 | -3 |
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
Precipitation (mm) | 16 | 17 | 28 | 35 | 47 | 39 | 31 | 24 | 24 | 31 | 25 | 19 |
Days with rain | 5 | 5 | 11 | 12 | 15 | 13 | 13 | 10 | 10 | 10 | 8 | 6 |
Days with snow | 8 | 7 | 3 | - | - | - | - | - | - | - | 2 | 6 |
Dry days | 18 | 16 | 17 | 18 | 16 | 17 | 18 | 21 | 20 | 21 | 20 | 19 |
Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
Sun hours per day | 4 | 4 | 7 | 9 | 9 | 11 | 10 | 10 | 9 | 6 | 5 | 4 |
Wind force (Bft) | 3 | 3 | 3 | 3 | 3 | 3 | 2 | 2 | 3 | 3 | 3 | 3 |
UV-index | 2 | 2 | 3 | 4 | 5 | 6 | 6 | 6 | 5 | 3 | 2 | 2 |
Best time to visit Illinois
The best time to visit Illinois in the United States is May through September. In this period you have a warm temperature and almost no precipitation. The highest average temperature in the state of Illinois is 28°C in July and the lowest is-1°C in January.
Climate of Illinois by month
What is the average climate in a given month for Illinois? Click on a month to see all monthly averages for sunshine, maximum and minimum temperatures, percent chance of rain per day, snowfall and number of rainy days.
Illinois weather experiences
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