- Integrated Surface Dataset (ISD) station ID: 725300
- Country: US
- State: IL
- Latitude: 41.96
- Longitude: -87.932
A Weather Bureau Army Navy (WBAN) station ID was found for this station. Older data may be available at the WBAN page.
High Temperatures
On May 21 in CHICAGO O'HARE INTERNATIONAL the average high temperature is 74.2 °F (23.5 °C). The lowest recored high temperature was 55.9 °F (13.3 °C) in 2025 and the highest recored high temperature was 92.8 °F (33.8 °C) in 1977. The high temperature is usually* between 67.9 °F (20.0 °C) and 80.5 °F (26.9 °C). About a quarter of the time, the high temperature is less than 67.9 °F (20.0 °C), and another quarter of the time, the high temperature is greater than and 80.5 °F (26.9 °C). About 95% of the time, the high temperature has been between 56.0 °F (13.3 °C) and 92.4 °F (33.6 °C).
Low Temperatures
On May 21 in CHICAGO O'HARE INTERNATIONAL the average low temperature is 49.6 °F (9.8 °C). The lowest recored low temperature was 30.9 °F (-0.6 °C) in 2002 and the lowest recored low temperature was 66.9 °F (19.4 °C) in 1977. The low temperature is usually* between 43.7 °F (6.5 °C) and 55.4 °F (13.0 °C). About a quarter of the time, the low temperature is less than 43.7 °F (6.5 °C), and another quarter of the time, the low temperature is greater than and 55.4 °F (13.0 °C). About 95% of the time, the low temperature has been between 32.6 °F (0.4 °C) and 66.5 °F (19.2 °C).
Frost
On May 21 in CHICAGO O'HARE INTERNATIONAL expect the temperatures to drop below freezing for a risk of frost about 2.1% of the time.
Data Source(s)
The data used to compute the average high/low temperatures for this location were taken from the following stations: