By Megan Glaros

CHICAGO (CBS) — Don’t get used to the sunny skies and pleasant temperatures that were dominating the Chicago area in the midday hours.

Clouds and a possible shower are on tap for the evening, and by the end of the week, you’ll be shivering without a jacket even in the mid-afternoon.

CBS 2 Meteorologist Megan Glaros says as of 11:20 a.m., it was 67 degrees at O’Hare International Airport and 68 degrees at Midway, 64 degrees in Waukegan and 70 degrees in Joliet.

Cloud cover continued primarily south of the city, but the city of Chicago itself had a pocket of clear air that continued straight back to the west all the way to Rockford.

Still, an isolated shower is a possibility for later in the day. The forecast high is 68, but many areas may see – or already have seen – the lower 70s.

An upper-level low-pressure system is expected to bring possible showers later Tuesday afternoon, as well as overnight, when the low drops to 57.

On Wednesday, more rain is expected as the high hits a forecast 70 with a south wind of 5 to 10 mph. And on Thursday, the high is expected to hit 73, with a chance for still more rain as a cold front plows through.

When that cold front passes, get ready for a bit of a shocker. The high for Friday is only 56 degrees, Saturday 54, and Sunday only 53.