How rainy have Good Fridays been?

Dear Tom,
My mother—whose Chicago weather experience now covers 97 springs—has observed that Good Fridays always seem to be rainy. How wet are they in fact?

Thanks,
Tom Gregg Niles

Dear Tom,
Your mother is correct and it has rained again this year. Good Friday weather does show a significant wet bias, be it rain or snow. We asked Chicago weather historian Frank Wachowski to examine the weather conditions on Chicago’s 147 Good Fridays dating back to 1871, and measurable precipitation has occurred 74 times, more than half of the years, at a time of year when the daily climatological expectation for precipitation is about 40 percent. When traces of rain or snow are added to the mix, it jumps to 63 percent compared to an expectation of 56 percent. The city’s last significant precipitation on Good Friday was in 2011 when more than half an inch of rain fell.