Cool September ends, but mid-summer warmth beckons
Illinois State Climatologist Jim Angel reports that this September will go down as this state’s 22nd coolest since 1895, with statewide temperatures averaging some 2 degrees below normal. Chicago readings the last six days have been subnormal, and September temperatures will average nearly 1.5 degrees below the most recent 30-year norms. However, the warm front moving east through Illinois today will be followed by slowly strengthening southerly winds that will more than counterbalance the diminishing daylight and lower sun angle, ushering in a significant warm-up that will see highs warm into the 70s Sunday with July-like highs in the mid 80s projected Monday and Tuesday—temperature levels more than 15 degrees above early October normals. Actually, back-to-back 80s are not all that unusual. Chicago weather records at Midway Airport dating back to 1928 reveal 44 of the 78 Octobers (56 percent) have experienced consecutive 80°-plus days.
--By Paul Dailey, WGN Weather Center Meteorologist