SIOUX FALLS, S.D. (KELO) — The coldest air of the season will be found across part of KELOLAND this weekend.

What exactly is the difference between a frost and a freeze as the temperature drops below the freezing mark?

Our recent hot spell is officially over and now full autumn weather means frost and freeze headlines have returned to the region.

Most of the central and northern plains are experiencing the first round of sub freezing temperatures of the fall. Temperatures in the lower 30s will certainly produce areas of widespread frost. However, those temperatures do not qualify for a hard freeze.

A hard freeze is defined as temperatures at or below 28 for at least TWO consecutive hours. Those conditions are not likely to be widespread this weekend.

So while your tomatoes and flowers may not like the cold, it’s probably not cold enough to kill off some of those pollen producers for allergy sufferers. Also, remember the coldest temperatures are usually found in rural locations and valley areas away from the city. Areas in the middle of Sioux Falls can often be several degrees warmer due to the urban heat island effect.

This cooler air will be sticking around into the days ahead with plenty more 30s for lows in the forecast.