Unseasonably chilly air swept into the area Friday, in the wake of yet another round of drenching thunderstorms. The 68-degree readings observed at both O’Hare and Midway airports were the coolest August 4th high temperatures in 46 years. The record lowest high temperature for the date remains a 62 degree reading that occurred in 1915. Cool air is to remain in place over the next ten days. Medium range forecasts suggest that temperatures will average about 5 degrees below normal through August 14th, a product of persistent northwesterly jet stream flow. While chilly air dominates the Great lakes region, record heat continues in the West. Warnings for elevated fire risk, and advisories for poor air quality cover much of the Pacific northwest.