Following one of the coolest, wettest and dreariest springs in recent memory, the city is about to experience an extended period of summer-level warmth and humidity. Temperatures are expected to climb into the 80s on Sunday and remain there daily through the upcoming week, something that has not occurred in Chicago since last summer when the city logged 23 straight 80-degree plus days from July 28-August 19. Saturday’s highs should hold in the 70s inland, but the persistent east winds that have dominated this spring will hold lakeside readings in the 60s. Showers and thunderstorms should develop Saturday night as the warm and humid air mass approaches the city, once again bringing the specter of heavy rainfall to a water-logged Chicago area. The shower threat will decrease after Monday as building high pressure pushes the shower threat zone north into the upper Midwest.