Father’s Day dawned warm and muggy, establishing a new record high minimum of 78 degrees for June 17, breaking the 1984 record of 77.
By afternoon, the mercury surged into the lower and middle 90s which, in combination with low and mid 70 dew points, sent heat indices to dangerous levels as high as 109. The steamy atmosphere eventually fueled isolated thunderstorms that brought brief relief from the stifling heat to a few locations.
The hot and humid conditions will persist Monday before a late-afternoon cold front ushers in several days of more comfortable conditions for the rest of the week, with persistent lake winds enhancing the cooling.
The cooler weather will come at a price, however, with several periods of showers and thunderstorms adding to the already robust precipitation totals logged in Chicago so far in 2018.