More rain falls in August on average than in any other month of the year here. August’s 4.62” tally is nearly an inch higher than runner-up April’s 3.68”.
By this time of year, months of warm weather have allowed a huge volume of moisture to accumulate in the atmosphere over the U.S.—moisture which can be harnessed by thunderstorms that tend to move more slowly than their counterparts at other times of the year. This makes them especially prolific rain-producers. More 1”+ and 2”+ downpours have soaked Chicago in August than in any other month. The month is 3.5 times more likely to generate a 1”+ rain than February (the month with the fewest days of heavy precipitation historically) and 45 times more likely than February to host a 2”+ rain.
Interestingly, rainfall Friday will bring the number of days of measurable precipitation since records began in Chicago back in November, 1870 to 16,850.
-Tom Skilling
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
