Illinois (Chicago)
May
Weather in Illinois for May 2026
Your guide to Illinois weather in May - trends and predictions
In general, the average temperature in Illinois at the beginning of May is 14.1 °F. As the month progressed, temperatures tended to significantly warm up, reaching an average of 18.1 °F by the end of May.
Illinois experiences heavy rainfall in May, with over 20 rainy days and an average total precipitation 134.2 mm.
New! Chat with our AI weatherman - it’s amazing and free.
Temperatures
Rain 🌧️
More
6
Dry days
25
Rainy days
0
Snow days
17°/11°
Temperatures
20 km/h
Avg max wind
71 %
Avg humidity
Illinois Weather May
Move between months or click on a day
What’s the Weather Like in Illinois This May?
Discover the average temperatures and weather trends across Illinois’s cities this May.
Temperatures trend during May in Illinois
See the weather trend as well as the moving average line
May weather in Illinois day by day
Click on a date for more information
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| May 1 |  Patchy rain possible | 16° /7° | 2.9 mm | 4 | |
| May 2 | Patchy rain possible | 15° /8° | 2.4 mm | 3 | |
| May 3 |  Heavy rain at times | 13° /7° | 9.7 mm | 3 | |
| May 4 |  Overcast | 13° /6° | 9.1 mm | 3 | |
| May 5 |  Sunny | 13° /7° | 3.1 mm | 3 | |
| May 6 |  Moderate or heavy rain shower | 13° /7° | 5.9 mm | 3 | |
| May 7 | Moderate or heavy rain shower | 16° /8° | 9.3 mm | 4 | |
| May 8 |  Cloudy | 15° /8° | 10 mm | 4 | |
| May 9 | Sunny | 14° /7° | 10.9 mm | 4 | |
| May 10 | Cloudy | 17° /8° | 0.2 mm | 4 | |
| May 11 |  Partly cloudy | 17° /11° | 0.6 mm | 4 | |
| May 12 | Sunny | 18° /10° | 3 mm | 5 | |
| May 13 | Sunny | 19° /12° | 5 mm | 5 | |
| May 14 | Partly cloudy | 16° /10° | 3.3 mm | 4 | |
| May 15 | Moderate or heavy rain shower | 17° /10° | 2.8 mm | 4 | |
| May 16 | Overcast | 21° /11° | 3.4 mm | 5 | |
| May 17 | Overcast | 16° /10° | 2.1 mm | 4 | |
| May 18 | Heavy rain at times | 17° /10° | 1.9 mm | 4 | |
| May 19 | Patchy rain possible | 19° /11° | 4.9 mm | 5 | |
| May 20 | Partly cloudy | 20° /12° | 21.3 mm | 5 | |
| May 21 | Moderate or heavy rain shower | 19° /12° | 14.5 mm | 5 | |
| May 22 | Overcast | 18° /12° | 0.2 mm | 4 | |
| May 23 | Sunny | 19° /12° | 0.9 mm | 5 | |
| May 24 | Cloudy | 18° /11° | 3.3 mm | 4 | |
| May 25 | Sunny | 18° /11° | 2.3 mm | 5 | |
| May 26 | Heavy rain at times | 18° /11° | 5.5 mm | 4 | |
| May 27 | Moderate or heavy rain shower | 15° /11° | 6.5 mm | 4 | |
| May 28 | Moderate rain at times | 16° /10° | 2.2 mm | 4 | |
| May 29 | Sunny | 18° /11° | 0 mm | 5 | |
| May 30 | Cloudy | 21° /13° | 0.5 mm | 5 | |
| May 31 | Partly cloudy | 21° /14° | 1.4 mm | 5 | |
| Next | |||||
Important Notice
Our weather forecast for Illinois in May is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Illinois forecast closer to your planned date for the most up-to-date weather information.
Change Month
Illinois in May - FAQ
What are the expected maximum and minimum temperatures in Illinois during May?
Enjoy moderate daytime temperatures of up to 17° and cooler nights around 11°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Illinois during May?
Significant rainfall exceeding 134.2 mm is expected in Illinois during May, occurring over more than 25 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Illinois during May?
The average wind speed in Illinois during May is 20 km/h, suggesting breezy to windy conditions, depending on your activities.
May rainfall patterns in Illinois
Explore the daily rainfall trends and prepare for Illinoiss May weather 💧
UV exposure in Illinois during May
Stay informed about UV levels for safe outdoor activities throughout the month of May ☀️
Counties in Illinois
Select a county for an accurate weather forecast
Top locations in Illinois
Select a location for an accurate weather forecast
More Locations Quick links
More Illinois weather pages
You are here
Where is Illinois?Get accurate weather forecasts for Illinois, located at latitude 41.85 and longitude -87.65. Stay updated with localized weather information tailored for Illinois.
Found a mistake?
We appreciate your attention to details. Tell us here.