The September-like temperatures of the past few days are expected to moderate to more typical late summer levels by early next week.
Wind flow favoring cool air over the Great lakes is forecast to slowly weaken heading into the upcoming weekend, allowing area temperatures to reach seasonable levels by Sunday. As high pressure gradually drifts east of the region, prevailing southwest winds are expected to develop and usher tropical air across the Midwest.
By the middle of next week, temperatures are forecast to approach 90 degrees, a reading not officially observed in Chicago since July 19th. Medium range computer forecasts remain consistent in suggesting that temperatures will be above normal through the end of August. The influx of tropical air is also expected to bring an increased chance of t-storms.