SWOP Weekly Weather Discussion

HEADLINE

Near record warmth will prevail for Christmas Day...with above normal temperatures lingering into the New Year.

DISCUSSION

A flat west-to-east zonal flow pattern has established itself across the U.S...leading to considerably milder conditions than have been seen for several weeks. As upper troughing currently in place off the coast of British Columbia amplifies, a prominent downstream ridge of high pressure will develop across the Midwest and Ohio River Valley by the middle of the week. Given rising upper heights, southwesterly boundary layer flow, and partial sunshine at times...record high temperatures will be likely on Christmas Day. Average highs on December 25th are in the middle to upper 30s, while the current forecast suggests readings will climb well into the 60s. Actual records for the date range from 63 degrees at Peoria to 64 degrees at both Lincoln and Springfield. The unseasonably warm weather will continue through the end of the week before the West Coast upper trough gets ejected eastward across the Plains and into the Midwest by next weekend. This will send temperatures back down to seasonal norms in the 30s by December 28th. The cool-down looks to be short-lived however, as longer range models all show upper heights once again rising by the end of the month into the first week of January.

The Eastern Pacific Oscillation (EPO) is currently in a positive phase, but is projected to briefly become negative around Christmas before quickly rebounding into positive territory through the first of January. This suggests the persistent La Nina pattern featuring an upper ridge over the northeastern Pacific Ocean and a downstream trough over Canada into the central U.S. has been temporarily broken. As a result, overall above normal temperatures are favored across central Illinois.

The latest 6-10 day outlooks (Dec 27-Dec 31) from the Climate Prediction Center (CPC) suggest ABOVE normal temperatures and NEAR normal precipitation across central Illinois.

Issued: 12/21/25