ll-Like Air Settles In Before Unsettled Mid-Week Pattern

According to the National Weather Service in Chicago/Romeoville, a post-frontal airmass is delivering cool, less humid conditions across northern Illinois and Northwest Indiana today. High temperatures will hover comfortably in the lower 70s near the lake to the mid-70s further south under mostly cloudy afternoon skies. While a shortwave disturbance may squeeze out a few light afternoon showers or an isolated rumble of thunder, dry air in the lower levels will keep accumulations minimal. High pressure builds directly overhead tonight, clearing skies and allowing overnight lows to tumble into the upper 40s and low 50s away from the urban heat islands.

National Weather Service

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Quiet conditions persist into Monday before a major pattern shift arrives. A strengthening Canadian surface low will push a warm front northward Monday night, sending humidity levels spiking with precipitable water values approaching two inches. This sets the stage for waves of heavy rain and potential thunderstorms tracking across the regional outlook from Tuesday through Thursday as a slow-moving cold front stalls over the area.

National Weather Service

Local 7-Day Forecast (Aurora / Chicago Metro Area)

Day Conditions High / Low (°F) Rain Risk

Sunday, Sep 13 Mostly cloudy, cool; slight shower risk 73° / 49° 25%

Monday, Sep 14 Partly to mostly cloudy, pleasant 74° / 62° 10%

Tuesday, Sep 15 Showers and thunderstorms likely 80° / 64° 90%

Wednesday, Sep 16 Periods of heavy rain and thunderstorms 76° / 63° 95%

Thursday, Sep 17 Scattered showers lingering 74° / 60° 60%

Friday, Sep 18 Brief drier break, partly sunny 75° / 58° 20%

Saturday, Sep 19 Next disturbance brings renewed showers 73° / 57° 70%

National 7-Day Outlook Highlights

On the national scale, a contrasting weather pattern dominates: the western United States faces elevated to critical fire weather conditions due to dry, breezy winds, while a tropical-infused moisture plume feeds persistent heavy rainfall across the Gulf Coast and Southeast. Meanwhile, a sweeping frontal system brings early-fall chill and intermittent showers across the Northern Plains and Great Lakes, linking up directly with our local mid-week system.

National Weather Service

Day National Synoptic Summary Primary Active Regions

Sunday, Sep 13 High pressure East; fire weather concerns West Northern Plains, Intermountain West, Great Lakes

Monday, Sep 14 Moisture surge pooling ahead of central Canadian low Central Plains, Upper Midwest, Gulf Coast

Tuesday, Sep 15 Heavy convective clusters along stalled boundary Midwest, Lower Mississippi Valley, Southern Plains

Wednesday, Sep 16 Flood watches possible under slow-moving frontal waves Great Lakes, Ohio Valley, Southeast

Thursday, Sep 17 Eastern trough deepens; cooler air pushes south East Coast, Great Lakes, Deep South

Friday, Sep 18 Transitional inter-system lull High Plains, Northeast, Intermountain West

Saturday, Sep 19 Pacific frontal wave driving onshore moisture Pacific Northwest, Northern Rockies, Central Plains