Chicago Weather: Warm Spell Ending, Winter Storm Expected Later This Week

CHICAGO (CBS) -- The warm temperatures come to an end as a cool-down takes place most of the week.

On Sunday night, look for increasing clouds and a low around 30. Rain comes Monday evening and turns to a rain/snow mix overnight Monday into Tuesday, and then all snow on Tuesday.

Beginning Tuesday and continuing through Wednesday, some accumulation of snow likely in our western and northwestern viewing area through Wednesday.

A Winter Storm Watch is in place for McHenry, Lake, DeKalb and Kane Counties for Tuesday morning through Wednesday morning.

Significant Accumulation could be possible in our western viewing area. Some slight change to the forecast could shift significant accumulation to Chicago.

It is possible that this will be upgraded to a Winter Weather Advisory or Winter Storm Warning for some counties by Monday.

Temperatures drop through Thursday and Friday.