Chicago Weather in May
May brings plenty of pleasantly warm weather to Chicago, Illinois. This is also the city's least humid month of the year.
This page gives detailed information on the typical May temperature, precipitation, sun, humidity, wind and storms for Chicago. The numbers here are historical averages based on temperature, rain and snow measurements gathered at Chicago Midway Airport and other climate data from Chicago O'Hare International Airport.
Temperature
| 72 °F | May average high | 22 °C |
| 52 °F | May average low | 11 °C |
| 17 days | 70 °F max. or more (21 °C) |
| 15 days | 50 °F min. or less (10 °C) |
The temperature usually rises every day in May to over 50 degrees Fahrenheit (10 degrees Celsius) in Chicago. The city averages 8 days this month when the thermometer reaches into the 80s °F (over 26 °C). Temperatures above 90 °F (32 °C) occur on average one day in May.
The thermometer dips to 40 °F (4 °C) or below on 2 nights. Frost is not expected here during May.
Rain
| 4.8 in | total precipitation | 121 mm |
| 12 days | of rain |
Half the time, Chicago receives 4.2 to 6.0 inches (107 to 153 mm) of rainfall in May. One in four years has drier weather, while another one in four is wetter. None of the precipitation falls as snow.
Sun
| 58 % | sunshine |
| 7 days | clear skies |
The sun's rays reach the ground in Chicago during 58 percent of daylight hours on average in May, for a total of 262 hours in the month. Typically on 7 days this month the sky is mainly clear, with at most 30 percent cloud cover.
Sunlight in May at Chicago lasts for 14 hours and 34 minutes a day on average. The shortest day of the month is the 1st with 14 hours and 3 minutes of daylight. By the end of the month, the days have lengthened to 15:00 from sunrise to sunset. These durations can vary by a minute or two from year to year.
Humidity
| 64 % | May average humidity |
The relative humidity in Chicago during May usually peaks at 77 percent in the morning then drops to 51 percent by mid afternoon. May is the least humid month for Chicago.
| Local Time | 12 am | 3 am | 6 am | 9 am | 12 pm | 3 pm | 6 pm | 9 pm |
| Humidity % | 73 | 77 | 77 | 61 | 53 | 51 | 54 | 66 |
Wind
| 10.5 mph | May wind speed average | 16.9 kph |
May is a little windier than most other months in Chicago.
Storms
| 3 days | rainfall of 0.5 inches (13 mm) or more |
| 5 days | with thunderstorms in May |
May is an average month for storm activity around Chicago.
Reference
The weather data here are long-term averages provided by the US National Centers for Environmental Information (NCEI). Temperature and precipitation are 1991-2020 normals while humidity and thunderstorms are 1961-1990 normals.