September 20 - Chicago - Weather History and Averages

High Temperatures

On September 20 in Chicago, IL (Illinois), USA the average high temperature is 75.1 °F (23.9 °C). The lowest recored high temperature was 55.0 °F (12.8 °C) in 1962 and the highest recored high temperature was 95.0 °F (35.0 °C) in 2018. The high temperature is usually* between 69.4 °F (20.8 °C) and 80.8 °F (27.1 °C). About a quarter of the time, the high temperature is less than 69.4 °F (20.8 °C), and another quarter of the time, the high temperature is greater than and 80.8 °F (27.1 °C). About 95% of the time, the high temperature has been between 58.7 °F (14.8 °C) and 91.5 °F (33.1 °C).

Low Temperatures

On September 20 in Chicago, IL (Illinois), USA the average low temperature is 57.5 °F (14.2 °C). The lowest recored low temperature was 32.0 °F (0.0 °C) in 1956 and the lowest recored low temperature was 73.9 °F (23.3 °C) in 2024. The low temperature is usually* between 52.3 °F (11.3 °C) and 62.6 °F (17.0 °C). About a quarter of the time, the low temperature is less than 52.3 °F (11.3 °C), and another quarter of the time, the low temperature is greater than and 62.6 °F (17.0 °C). About 95% of the time, the low temperature has been between 42.6 °F (5.9 °C) and 72.4 °F (22.4 °C).

Frost

On September 20 in Chicago, IL (Illinois), USA expect the temperatures to drop below freezing for a risk of frost about 0.0% of the time.

Usually* in this context means around 50% of the time, assuming a normal distribution of values.

Data Source(s)

The data used to compute the average high/low temperatures for this location were taken from the following stations: