For the first time since the start of Fall the overnight low temperature fell into the 30s for Rockford, officially dropping to 35 degrees Sunday morning. Even though it was closer to our normal low temperature for mid-October (low 40s) it felt a lot cooler than what we’ve been used to these last several weeks.
As our average high and low temperatures typically begin cooling during the months of September and October, our actual highs and lows have been doing the opposite. September was a warm month, averaging almost five degrees above the monthly average, and the first two weeks of October were the warmest first two weeks of October – ever – for Rockford! Low temperatures for the first half of October have been exceptionally warm, averaging the mid 50s to mid 60s. It’s only been within the last few days that we’ve felt the overnight low temperature drop to where it should be this time of the month.
The warmer nights/mornings have also helped with the high temperatures during the afternoon, keeping them above average. Now while the warmer days and nights are a cause for celebration for some, it’s important to look at the potential impacts that these warmer days have on the things around us. The drier and warmer than normal conditions have caused the Fall colors to be delayed across the region, kept humidity levels higher impacting those who may be suffering from asthma or allergies, summer bugs/pests have been around a little longer, etc.
Our warming climate has also had an impact on when our first Fall freeze occurs. Since 1970, Rockford’s first Fall freeze is now occurring, on average, 15 days later than when it did 50 years ago! The average first 32 degree temperature for northern Illinois typically occurs within the first week, to week and a half, of the month of October. As of October 17th, our overnight low temperature has failed to reach 32 degrees; and it looks like the warmer temperatures will continue through at least the upcoming week, if not beyond. Locally, it is the low temperature that is warming more than the high temperature – overnight lows not cooling as fast, or as low, as what they were over the last 30-40 years. The Winter season is the faster warming season, impacting areas in the Arctic where sea ice loss has been within record territory, if not passing it, within the last few years.
Our overnight low temperatures will warm again this week, but then are forecast to drop back into the 30s by the end of the week and start of the weekend following a cold front. It’s possible that some spots could dip near 32 degrees across Iowa, Wisconsin and northern Illinois, but widespread freezing temperatures don’t look too promising.