Dear Tom,
What constitutes a sunny day?
How many sunny days a year does Chicago get as compared to southeast Florida?
Mike Priory, Ft. Lauderdale
Dear Mike,
We checked with Chicago climatologist Frank Wachowski, who maintains Chicago’s
sunshine records, and he told us that while the definition is somewhat subjective, he
considers a day to be sunny if it has less than three-tenths cloud cover in daylight and
records 90 percent or more of the possible sunshine. Believe it or not, Chicago averages
83 sunny days a year, compared with only 74 in southeast Florida, a result of the almost
daily clouds that form in the tropical Florida air masses. However, a more realistic
comparison would be in percent of possible sunshine, and southeast Florida wins that
hands down, logging around 70 percent annually compared with Chicago’s 54 percent.
