CHICAGO — A major weather pattern shift is on the way.

A third consecutive day with highs in the 70s is ahead for most areas Thursday, except immediate lakeshore where southeast winds will hold temperatures to the mid to upper 60s.

The mild weather will spill over into Friday morning but showers and scattered thunderstorms are expected to develop ahead of a strong cold front. It will bring the warmth to an unceremonious end.

The chilliest air in 5-plus months will follow. Readings will plunge from 74 degrees on Thursday and near 70 degrees Friday morning to near freezing by Saturday morning.

Frost and freeze has potential for outlying areas away from the warmth of Lake Michigan.

In addition to the chilly temperatures, gusty West winds will create wind chills in the lower to middle 20s by daybreak Saturday.