WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.

Books close on a cool, cloudy summer

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September's arrival signals that meteorological autumn is under way. Weather records closed overnight on one of the area's truly peculiar summers. It ended with a string of daytime highs that failed to reach 70 degrees at a time of the year when upper 70s are common. An August that closes with five back-to-back days during which the temperature failed to break out of the 60s hasn't occurred here in 118 years. The summer season hosted 18 such days---more than triple the average of five such days.

Summer short on sun

But perhaps one of this summers most lasting legacies was its lack of sunshine. Summer 2009 goes down in the books as the cloudiest on record. Never since sunshine records began 115 years ago has a June-through-August period hosted less of the possible sunshine. Sunshine is measured in minutes and the summer's total was 42,887 of the season's possible 80,626 minutes of sun, or 53 percent of possible sunshine---67 percent is considered normal.

Days continue to shorten in September, taking a toll on temperatures. 120 minutes of sunshine disappears by month's end and normal highs fall from 78 to 69-degrees.


TROPICAL UPDATE

Powerhouse Hurricane Jimena with near Category 5 strength 155 m.p.h. sustained winds continues churning toward the Baja California peninsula. Cabo San Lucas is among the areas under a hurricane warning.