Chicago (IL) Monthly Rainfall & Precipitation
This page shows both the average monthly rainfall and the number of rainy days in Chicago, Illinois, United States of America. Long-term data from 1990 to 2020 was used to calculate these averages. Now, let's explore all the details to give you a full picture.
Chicago is known for its substantial rain/snowfall, with annual precipitation reaching 1062 mm (42 in).
Monthly Precipitation Levels
The average number of days each month with precipitation (> 0.2 mm (0.01 in))
Significant seasonal changes in precipitation occur throughout the year. During the wettest month, June receives substantial rainfall, averaging 126 mm (5 in) of precipitation, recorded across 14 rainy days.
In contrast, the driest month, January brings less snowfall, with 50 mm (2 in) over 10 snowy days.
June, the wettest month, has a maximum daytime temperature of 26°C (79°F). The city receives 311 hours of sunshine in this period. During the driest month January you can expect a temperature of -1°C (30°F). For more detailed insights into the city's temperatures, visit our Chicago Temperature page.
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in July
Explore Chicago's Historical Precipitation: 1976-2026
Browse day-by-day precipitation records for Chicago spanning 51 years. Select any month and year to see actual rainfall and snowfall recorded on each day.
Annual Rainfall in the United States of America: City Comparison
The map below shows the annual precipitation across the United States of America. You can also select the different months in case you are interested in a specific month.
heavy rainfall
high
moderate
low
almost none
Chicago vs World: Rainfall Compared
Chicago's average annual precipitation is 1062 mm (42 in). Let's compare this to some popular worldwide tourist destinations:
The city of Rome, Italy, has an average annual precipitation of 832 mm (33 in), spread fairly evenly throughout the year.
In Seoul, South Korea, the average annual precipitation is 1237 mm (49 in), with most rain falling during the summer monsoon season.
In Brisbane, Australia, the annual precipitation is 979 mm (39 in), making it wetter than Sydney.
Bangkok, Thailand, experiences a tropical monsoon climate with 1668 mm (66 in) of annual rainfall, with the heaviest precipitation occurring during September and October.
Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.
Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.
Climate change is affecting precipitation patterns worldwide, including Chicago (IL):
- Changing Rainfall Patterns: Global warming causes drastic changes in the patterns of rainfall. Some areas have been experiencing increased frequency and intensity of rainfall, while other areas experience longer dry spells or even droughts.
- Local Impacts: Many regions are experiencing heavier rainfall in the winter months and drier, hotter summers. This affects agriculture, water resources, and ecosystems.
- The U.S. has a significant number of thunderstorms every year, with over 14.6 million taking place across the world annually.
- Approximately 70% of lightning bolts strike land rather than oceans.
- A storm named John was the longest-lasting Pacific tropical storm, continuing for 31 days. As it crossed the dateline twice, it changed status from a hurricane to a typhoon and back to a hurricane.
For more detailed information about Chicago (IL)'s weather, including sunshine hours, humidity levels, and temperature data, visit our Chicago (IL) Climate page.
