A slide toward La Nina conditions, which began with unusual speed across the equatorial Pacific in February, may impact Chicago’s summer weather. A series of computer forecasts predict a La Nina of at least moderate intensity. Equatorial Pacific Ocean temps may end up as much as 1.5 to 3° cooler than normal—signaling a well developed La Nina. Though La Nina’s global effects are generally considered less pervasive than El Ninos, in-house analyses have linked a slight tendency toward wetter than normal springs with the event. Stronger La Ninas have impacted summer weather as well. In eight of nine warm seasons since 1950 identified as having coincided with La Ninas comparable to the one predicted this summer, Chicago temps have averaged warmer than normal overall from June through August. These years have produced an average of 33 days of 90s at Midway Airport—more than the average of 24 since 1928.
--By Tom Skilling, WGN-TV Chief Meteorologist
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
