When should Chicago see its last 70s, 60s and 50s this year?
Chicago - Our fall has felt a lot more like summer on several occasions.
We had five straight days with highs in the 80s that started on the last day of September and continued through the first four days of October. During that stretch, Chicago's temperatures felt just like July coming in nearly 16 degrees above average. The odds of seeing summer-like weather will be dropping dramatically over the coming days.
We are now on a streak of below-average days. Today will be the fifth straight cooler-than-average day.
The 80s may be over for 2023. We typically see the last day of the year with a high of 80 or warmer around Oct. 5. We have hit 80 degrees as late as Nov. 11, 1950. That day the mercury climbed to 85 degrees. Based on the longer-term forecasts for the next few weeks, I would not bet on any additional 80s this year. What about more 70s?
Here are the average last dates and mean (or typical) last dates for hitting highs in the 70s, 60s, and 50s:
- Mean last 70 degree high or warmer is Oct. 30
- Record last 70 degree high was Dec. 3rd, 2012
- Mean last 60 degree high or warmer is Nov. 25
- Record last 60 degree high was Dec. 31, 1875
- Mean last 50 degree high or warmer is Dec. 13th
November sees the most dramatic drop in average temperatures of any month during the year. The mercury drops 13.7 degrees from the average high on the first of the month to the average high on the last day of the month. October is just behind with the average high dropping 13.5 degrees over the course of the month.
A contributor to our turning cooler is the steady drop in daylight. We lose nearly three minutes of it each day in October and when November starts we are losing just over two minutes a day. By the end of November, we are losing about a minute and a half of daylight per day. By the end of fall on Nov. 31, we will lose nearly two hours of daylight compared to today.
Our Fox Model keeps highs cooler than average for the next eleven days. Average highs for Oct. 10th are around 65 degrees and fall to 61 degrees by the 20th. The cool keeps coming.
The longer-range temperature outlooks from the Climate Prediction Center hints at a cool pattern first and then transition back to normal.
The 6-10 day temperature outlook has most of northern Illinois "leaning below" normal overall. This covers the period of Sunday through the following Thursday.
The 8-14 day temperature outlook also has us bouncing back to near normal overall for the period from next Tuesday through the following Monday.
The even longer range 3-4 week outlook favors us for below-average temperatures overall for the end of October into the first few days of November. Cool patterns eventually turn colder which means we start looking for the first flakes of snow to fly. The average first day for that is about three weeks away.