SIOUX FALLS, S.D. (KELO) — After a prolonged period of mild weather, the weather is finally showing signs of change. As it turns out, the timing of the colder weather is right on cue.

A big cool down is coming for the northern plains this week. Temperatures will be several degrees below normal starting Thursday into Friday. This will likely push overnight lows into the frost and freeze range for parts of the region.

The timing of the colder weather is interesting. This map shows the average first 32 degree day morning in South Dakota during the fall season.

Most areas East River can expect 32 degrees by the first week of October.

Getting down to 28 degrees is a little harder. The calendar dates are usually pushed out another week or so when looking at those temperatures.

By the way, a killing freeze that ends the growing season is typically defined as 28 degrees or lower for three consecutive hours.

We may have some of those conditions around later this week, but not widespread across the region.