Extreme Weather in Illinois

By Duane Friend

Anyone that has lived in Illinois for more than a year knows we can experience a wide range of weather. It can be hot, cold, dry, wet, windy and humid, sometimes changing from one to the other very quickly. The following information on weather extremes comes from the Illinois State Climatologists office and the Midwest Regional Climate Center.

The highest temperature reported in Illinois was 117 F in East St. Louis on July 14, 1954.

Jacksonville is not far behind, with a high temperature of 114 F on the same day.

The lowest temperature reported in Illinois was -36 F in Congerville on January 5, 1999.

One has to go back to February 27 of 1934 to find Jacksonville’s lowest temperature of -28 F, which shows how late in the winter extreme cold can still occur.

The most rainfall from a single event was 16.94 inches in Aurora during a 24-hour period spanning July 17-18, 1996. I remember Jacksonville’s extreme of 5.02 inches on September 23 of 1993 well. We had just moved to town the week before and ended up with water seeping into the lower level of our house. I also know, at least anecdotally, that some areas close by have received much more than five inches in the past few years.

There have been two months in which Illinois has received no precipitation in the area- February in 1917 and September in 1979.

The most precipitation in a year was a virtual tie between New Burnside in 1950 (74.58 inches) and Carbondale in 1945 (74.50 inches). Just a hair under 60 inches occurred for our area in 1973, and the lowest annual precipitation here happened way back in 1901, when only 21.49 inches was received.

The most snow from a single event appears have occurred in Astoria on February 27-28, 1900, with 37.8 inches.

The most snow for a single winter was 105.1 inches at Antioch during the winter of 1978-1979.

We all know tornadoes are fairly common. The average time of day with the highest occurrence of tornadoes is 5 p.m.

Since 1950, the majority of tornadoes in the state have been in the EF0 category, which has winds of 65 to 85 miles per hour. There have been a little over 1,000 of these. While only forty EF4 tornadoes have been recorded, with winds of 166-200 miles per hour, this category created the most fatalities- over 100. EF stands for the Enhanced Fujita scale, named after the meteorologist who initially developed it.

Severe Weather Preparedness Week is February 28 through March 5. For more information, go to http://www.ready.gov/severe-weather , and visit the University of Illinois Extension Disaster Preparedness website at http://web.extension.illinois.edu/disaster/prep.cfm

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