This winter was the 5th warmest winter on record for Illinois. The statewide average temperature was 34.0 degrees, 4.9 degrees above the 1981-2010 normal. It actually beat out last winter, which was a surprise. Last winter was expected to be mild because of El Niño. Here are the top 10 mildest winters in Illinois history. Temperatures are in degrees F. Three of those top ten winters have occurred since 2000 and seven since 1980.
| Rank | Winter | Temperature | Departure |
| 1 | 1931-32 | 36.4 | 7.3 |
| 2 | 2001-02 | 34.7 | 5.6 |
| 3 | 1997-98 | 34.6 | 5.5 |
| 4 | 2011-12 | 34.5 | 5.4 |
| 5 | 2016-17 | 34 | 4.9 |
| 6 | 1991-92 | 33.9 | 4.8 |
| 7 | 2015-16 | 33.9 | 4.8 |
| 8 | 1982-83 | 33.6 | 4.5 |
| 9 | 1920-21 | 32.9 | 3.8 |
| 10 | 1918-19 | 32.8 | 3.7 |
Here are the winter temperatures in Illinois since 1895. There is a 1.7-degree warming per century. That doesn’t sound very spectacular. But what’s really happening is that we are getting more mild winters and fewer severe winters (highlighted). But what about 2013-14? That was the exception that proved the rule – a cold winter by modern standards, but not unusual by 1970s or early 20th century standards.
The U.S. winter temperatures show a similar warming trend. And temperatures for the Northern Hemisphere (since that’s winter for us) show strong warming since the 1980s (figure below).So it’s not just an Illinois pattern, but reflects global changes in temperature.
