Sustained northwesterly flow aloft supplied cool summertime airmasses to much of the Midwest and Great Lakes region during
July. Typical summer heat and humidity was largely kept at bay, with only a couple days seeing temperatures near or slightly above normal.
In Peoria, the average temperature during the month was 70.7 degrees, which was 4.4 degrees below normal. This was the coolest July on record in Peoria, breaking the old record of 71.2 degrees set in 1971. Daily record cool highs were set on the 1st (69 degrees), 18th (71), and 19th (73).
The average temperature for Lincoln was 69.4 degrees, which was 5.6 degrees below normal. This was the coolest July on record, breaking the record of 71.3 degrees in 1924. Record cool highs were set on July 1 (70), July 17 (72), and July 18 (71). Lincoln tied a record low of 49 degrees on the 20th.
In Springfield, the average temperature was 71.2 degrees, which was 5.1 degrees below normal. It was the 2nd coolest July on record, surpassed only by a 71.0 degree average in 1891. A daily record cool high was set on July 18th (71), while Springfield set a record low of 52 degrees on the 20th.
Here is a list of the top 5 coolest Julys on record for Champaign-Urbana:
Through July 30th, the average temperature for Champaign is 70.5 degrees (4.5 degrees below normal) and ranked as the 2nd coolest July on record. Daily record low highs were set on July 4 (67) and July 18 (73).
It is interesting to note that no 90 degree high temperatures were reached at these sites in July. This only happened in one other year, 2000. The warmest day at Peoria was 87 (15th) and the warmest day in Lincoln and Springfield was 86, both on the 7th. The coldest July monthly maximum temperature since 1948 was 88 in Peoria and Springfield, and 89 in Lincoln, all set in 2000. Champaign's highest temperature was 87 degrees (28th), Decatur was 86 (28th), Mattoon 87 (7th), Lawrenceville 88 (7th), and Bloomington 86 (15th). Central and southeast Illinois averages around a dozen 90+ degree high temperatures in a typical July.
Here are the average July temperatures for other central Illinois cities.
Below are graphs of the warmest July high temperature by year since 1948 for Peoria, Lincoln, and Springfield. Notice how 2009 (at the far right) is the coolest during the period of record.
Click images to enlarge
Here are a few interesting links: