Chicago will soon experience 'weather whiplash'

October has gotten off to a torrid start. Every day so far this month has hit highs in the middle to upper 80s. O'Hare is now running more than 15 degrees above average for the month. This is a continuation of an extended streak of unseasonably warm weather. 

Today will be the 15th straight day with above average temperatures.

There is a dramatic drop coming for this weekend. There will be a drop of nearly 50 degrees from the warmest part of this week to the coldest part of this weekend. Tuesday's high climbed to 87 degrees at O'Hare, just four degrees from tying a record that went back nearly 70 years. Temperatures will tumble to near 40 degrees by Sunday morning. Some spots well west and northwest of the city could dip into the upper 30s.

This will be a quick case of weather whiplash. Highs fall into the 50s this weekend for the coldest weekend in five months. By Wednesday next week we warm back into the 70s. Average highs this time of the year are in the middle 60s.

The longer-range temperature outlooks from the Climate Prediction Center shows a fairly strong signal for a warm-up coming quickly after our weekend cool down.

The 6-10 day temperature outlook has most of northern Illinois "leaning above" normal overall. This covers the period of next Monday through the following Friday. 

The 8-14 day temperature outlook also has us "leaning above" normal overall from next Wednesday through the following Tuesday. Most of the country is favored to be above average overall for the middle of the month.

The monthly temperature outlook for October also favors most of the country for a mild month. 

We are once again "leaning above" average for the period. If these forecasts verify, October would be the 9th above average month of the year so far. Only March has come in cooler than average so far in 2023.

The first month of meteorological fall ended up a little more than 3 degrees above average. 

September had an average temperature of 69.5 degrees. It tied two other years as the 14th warmest September on record for Chicago. That is right in line with the month's warming trend that goes back to 1970. Climate Central's study reports that Chicago's Septembers have warmed a little more than 3 degrees over the past nearly 50 years.

Fall is one of the fastest-warming seasons of the year. 

Climate Central also reports that the season has warmed nearly 2 degrees here since 1970. The betting line so far this season seems to indicate another warmer than average autumn.

Warmer falls mean more fall days above average. Climate Central says we are now seeing about 9 more days in fall that have exceeded the 1991-2020 normal for Chicago. We aren't the only location seeing a bump in above average fall days. 96% of the 231 locations they analyzed have seen an increase in the annual number of days with temperatures above average.