September has been quite warm thus far. In fact, we are flirting with the warmest average overall temperature ever for the month of September. There is one road block in the way that may disallow Rockford to record its warmest September ever, however. That is a large upper-level trough that is poised to move across the Midwest and Great Lakes early next week. That trough will be associated with a powerful early fall cold front that is going to move through late Sunday. The map above shows that trough (a dip in the flow) by looking thousands of feet into the atmosphere. The shades of green and yellow indicate much cooler air, and that will be around through the entire week.
This may be the cold front that fully eliminates summer-like heat and humidity from the forecast until 2017. Take a look at the graphic depicting our temperature trend into next week. We will be above average in the upper 70's and lower 80's this weekend, but highs will only be in the 60's and lower 70's next week with plenty of sunshine.