Sunday, Aug. 20
The center of high pressure shifts east, allowing strengthening southerly wind flow to bring hot and increasingly more humid air into northern Illinois and northwest Indiana.
Afternoon temperatures approach and even exceed 90°, while dew-points reach into the upper 60s.
Scattered clouds and a few whisps of cirrus invade the sky during the afternoon. Clouds increase overnight, holding temps from dropping much lower than 70-degrees.
South to southwest winds 10 to 20 miles per hour.
Monday, Aug. 21
Breezy as clouds increase, hot and and humid. Isolated t-storms may occur early and then again later in the day mainly north. Storms become more likely area-wide at night. Highs: 80s north to low 90s south. SSW winds 12 to 24 mph.
Tuesday, Aug. 22
Mostly cloudy with clusters of thunderstorms, severe storms with heavy downpours possible. Highs in the 70s north to mid 80s south. Storms end and skies clear overnight. SW winds 10-15 mph turn NW.
Wednesday, Aug. 23
Partly sunny. Gusty north to northeast winds steer colder less humid air into the area. Highs in the low to mid 70s and cooler yet along the lakefront. Clear skies overnight.
Thursday, Aug. 24
Canadian-source high pressure settles across the upper Midwest. Northeast winds here bring a cloud/sun mix with chilly temperatures – highs in the low 70s with mid/upper 60s lakeside. Clear skies overnight.
Friday, Aug. 25
Sunny with temperatures still 5-8 degrees below normal for this date – high temperatures in the middle 70s and even cooler at the lakefront with a light southeast flow. Clear skies overnight.
Saturday, Aug. 26
Mostly sunny and a little warmer with light south to southeast winds. High temperatures in the upper 70s – an on-shore flow developing in the afternoon keeps readings in the 70s at the lakefront.