A change in upper level wind flow is forecast to keep the core of mid-summer heat and humidity south and west of the Chicago area through the upcoming work week.
Thunderstorm clusters are expected to form along and north of a front separating hot temperatures over the Plains states, from cooler air over the Great Lakes. C
louds are forecast to be on the increase Sunday, but storms will stay mainly west of the region during the daylight hours. Showers may reach the area by Sunday evening.
As warmer, more humid air makes a move toward Chicago overnight, showers and storms are forecast to become heavier and more numerous. Periodic showers and storms are then possible through Tuesday. The clouds and showers are expected to keep temperatures below the 90-degree mark.
Dry, pleasant weather is due to return midweek as high pressure builds across the Great Lakes.