SIOUX FALLS, S.D. (KELO) — Labor Day Weekend summed up the summer with hot and mostly dry conditions, but things can quickly change in the month of September.

Northerly winds helped bring in cooler air after Labor Day as temperatures dropped at least 20 degrees in western South Dakota and at least 10 degrees in eastern KELOLAND. While we will be more seasonal for the rest of the week, falling temperatures in September are expected.

Here’s a look at the fastest-falling average highs. When you look at the climate average highs, September is the third quickest month for cooling. This holds true for Sioux Falls, Aberdeen and Pierre.

But, September is the fastest falling month for Rapid City as their average highs go from 80 at the beginning of the month to 66 by the end, a difference of 14 degrees.

Now that the heat is behind us, it’s time to bring on cooler weather. In fact, don’t be too surprised to hear about lows falling to the 40s by the middle of the month and even some 30-degree temperatures may be on the table.