weather in port byron, illinois fahrenheit
Illinois Weather > Port Byron Weather Port Byron, IL Weather Port Byron, IL climate is warm during summer when temperatures tend to be in the 70's and very cold during winter when temperatures tend to be in the 20's. The warmest month of the year is July with an average maximum temperature of 85.40 degrees Fahrenheit, while the coldest month of the year is January with an average minimum temperature of 13.20 degrees Fahrenheit.