CHICAGO (CBS) — “You need to have a coat ready, you need to have an umbrella ready, and you need to have a tank top ready, all for the next couple of days,” CBS 2 Meteorologist Megan Glaros tells us.

Why do we need this bizarre wardrobe? In the coming week – and for the second time in as many weeks – the conditions will change from those of July to October in a matter of days.

On Monday morning, the Chicago area started the day in the mid-60s. A warm front headed into the area from the southwest will jack temperatures up to the upper 80s, with a forecast high of 87 degrees, and the mercury likely to top out near 90 in some areas.

A gusty, roasting wind in excess of 20 to 25 mph will accompany the steamy temperatures.

But don’t look for it to last. A cold front and low pressure system will sweep into the Chicago area overnight, making for some showers around daybreak Tuesday.

Once skies clear, temperatures will take a plunge. The high for Tuesday is a comfortable 72, but drops to 67 on Wednesday when another blast of cool air comes in, and a nippy 62 on Thursday – 25 degrees below the high for Monday. On Thursday night, the low will be a chilly 49 degrees.

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