An expansive area of upper level high pressure will intensify over the middle of the Nation. This will bring a return to oppressive heat and humidity, beginning this weekend. Conditions appear similar to the most recent heat wave, except over a much longer time frame.
Across east-central Illinois, it appears that this heat wave will begin on Sunday, when highs reach the lower 90s, and heat index values climb to around 100 degrees. Then, extending into at least the middle of next week (perhaps longer), highs each day will likely be in the mid-90s. Afternoon heat index values each day will likely reach around 110 degrees over many areas. The nighttime hours will not provide much relief, as low temperatures only fall into the 70s.