Chill in Chicago's air feels like mid-April

It's the third day of meteorological summer-but it certainly doesn't
feel that way. Wednesday's predicted low 60s would be right at home in
mid-April. Highs as chilly as Tuesday's 60 degrees at O'Hare
International Airport and 61 at Midway Airport have occurred this late
in the season only 29 of the past 81 years (or, on average, about a
third of the time).

 Though it's far too early to write off summer heat, many Chicagoans
sense warm seasons haven't been as hot as they once were. It's a
proposition we investigated-and there's more than a shred of truth to
it. While Chicago's overall June-through-August average temperatures
have risen slowly the past five decades (from 72.5 degrees in the 1960s
to 73.9 degrees in the 1990s), the number of truly hot 90+-degree days
has waned. Since 2000, the annual average of 18.3 days at or above 90
degrees at Midway is down from 23.2 days in the 1980s and 21.1 days in
the 1990s. Summer days have cooled an average of 0.46 degrees since the
1990s while summer nights have warmed 1.64 degrees during the same
period.