Chicago Weather in October
October brings the beginning of cold weather to Chicago, Illinois. This month typically has the first frosts and in rare years, the first snowfall.
This page gives detailed information on the typical October 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.
|64 °F||October average high||18 °C|
|47 °F||October average low||8°C|
|19 days||60 °F max. or more (16 °C)|
|9 days||40 °F min. or less (4 °C)|
Nearly every October day warms to over 50 degrees Fahrenheit (10 degrees Celsius) in Chicago. The city averages 9 days this month when the thermometer reaches into the 70s °F (over 21 °C). Temperatures above 90 °F (32 °C) are not expected here during October.
This month the thermometer dips to freezing or below on an average of one night. Chicago does not normally get as cold as 20 °F (-8 °C) in October.
|3.9 in||total precipitation||98 mm|
|11 days||of rain or snowfall|
Half the time, Chicago receives 2.1 to 5.4 inches (54 to 137 mm) of precipitation in October. One in four years has drier weather, while another one in four is wetter. In rare years, some of the precipitation falls as snow.
|9 days||clear skies|
The sun's rays reach the ground in Chicago during 55 percent of daylight hours on average in October, for a total of 189 hours in the month. Typically on 9 days this month the sky is mainly clear, with at most 30 percent cloud cover.
Sunlight in October at Chicago lasts for 11 hours and 3 minutes a day on average. The longest day of the month is the 1st with 11 hours and 44 minutes of daylight. By the end of the month, the days have shortened to 10:24 from sunrise to sunset. These durations can vary by a minute or two from year to year.
|69 %||October average humidity|
The relative humidity in Chicago during October usually peaks at 81 percent in the morning then drops to 53 percent by early afternoon.
|Local Time||12 am||3 am||6 am||9 am||12 pm||3 pm||6 pm||9 pm|
|10.0 mph||October wind speed average||16.1 kph|
October is an average month for wind speed in Chicago.
|3 days||rainfall of 0.5 inches (13 mm) or more|
|2 days||with thunderstorms in October|
Thunderstorms occur much less frequently during October compared with previous months.
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.