What is the percentage of rain received in Chicago for the holiday since the city’s records began?

Dear Tom,

For the past 15 years I have tracked rain on the 4th of July and it has rained 33 percent of the time. What is the percentage of rain received in Chicago for the holiday since the city’s records began?

Thanks,
William J. Ooms Jr.
Alsip

Dear William,

Chicago’s July 4th weather records date back to 1871 and over those 148 years the city has received some rain (a trace or more) nearly half of the time. However, when considering just measurable rain (at least 0.01 inches), that percentage drops to 35 percent, about that same as during the last 15 years. The city’s recent Independence Days have been dry until this year when evening thunderstorms erupted. Officially, the city received just 0.01 inches, but heavier amounts fell across the south metro area putting a damper on fireworks displays. The holiday’s heaviest rains fell in 1995 when strong thunderstorms brought 1.72 inches of rain and small hail, and in 1883 when 1.60 inches of rain fell.