The same brisk southerly winds which delivered 80s to the Plains and western Midwest Monday bring Chicago unseasonable July-level temperatures Tuesday afternoon. It’s a development which sets the stage for the area’s warmest October open in 37 years. The last time a reading as warm occurred on Oct. 1 was 1976!
An 84-degree high would be 16-degrees above normal and would equal the normal maximum temp July 1-8!
September 2013 posts a 2.6-degree temp surplus; ranks among the city’s warmest 26% of past 143 years
The 3 month meteorological autumn season continues its warm ways. October’s unseasonable open follows September, 2013′s 2.6-degree temperature surplus—a reading which wound up more than 3-degrees warmer than September a year ago.
September 2013′s 67.2-degree average temperature makes it the 37th-warmest September of the past 143 years and places the month among the 26% warmest Septembers of the past 143 years.
Sunshine data helps explain some of the month’s warmth. Chicagoans have been treated to 72% of September’s possible sun. That exceeds the normal of 64%.
Normal highs slip from 68 to 56 in October
What’s ironic is the abnormally warm air with which October is opening is occurring in a month known to be Chicago’s 2nd-fastest cooling. Normal temp extremes dip from 68/48 on the first to 56/39 on October’s 31st and final day.
Resurging late week warmth and humidity sets the stage for much needed thunderstorm clusters; rainfall here since July 1 just 54% normal
Tuesday won’t be the week’s last warm day. While the day’s gusty south to southwest winds give way to modestly cooler northeast to east winds off Lake Michigan Wednesday, southerly winds ahead of a developing autumn storm are not only to produce a resurgence in temps here Thursday and Friday—they’re also to send humidities surging. That lays the groundwork for clusters of late week thunderstorms—some capable of downpours and gusty winds.
Model forecasts of Chicago area rainfall range from as little as 0.26” to as much as 3.32”.
The spread among those forecasts is wide—but warm season rains fall notoriously unevenly making that sort of range among the computer projections entirely possible.
The need for rain here is clear. The period since July 1 has recorded a paltry 6.48 inches of precipitation—an amount just 54% normal. The period from July 1 through Oct. 1 ranks as this area’s driest since 1976 and the 19th driest such period since 1871!
Incoming weekend chill to produce Fall 2013’s 3rd-coolest day Sunday
Temperatures dive over the weekend—particularly Saturday night and Sunday. Sunday’s 65-degree predicted high not only signals cool weather for the Bears game (which begins midday), it would also rank as the 3rd-coolest day of meteorological autumn 2013.