ST. LOUIS — The leaves are beginning to change and we know cooler air can't be too far away. Autumn is here even though it doesn't feel like it in St. Louis as we start October. The month of October brings changes to Missouri and Illinois and that usually includes the first frost of the fall season.
While the month has started with well above-average temperatures, a change for the first weekend of October is coming. Two cold fronts will sweep across the region during the middle of the week. By the weekend, early morning temperatures will drop into the 40s, and perhaps a few of the colder outlying areas drop into the 30s.
On average, the first frost of the year occurs in portions of the Ozarks during the first week of October when the temperature drops to 36 degrees.
With the colder air arriving this weekend, the chance of temperatures dropping into the mid-30s in a few colder spots has risen to over 50%. The National Weather Service said on Monday afternoon, a 50-70% probability exists of low temperature reaching 36 degrees. The most likely area is in the lowest, protected valley areas of Crawford, Dent, Iron, Reynolds and Washington counties in Missouri.
Click here for the full Weather First forecast.
The latest forecast drops temperatures into the middle 30s over the coldest parts of the Ozarks by Sunday morning. With a clear sky and light wind, patchy frost is becoming more likely in the colder portions of the 5 On Your Side area by Sunday morning.
The first freeze, when the air temperature drops to 32 degrees, can be expected in the colder areas by the middle of October on both sides of the river.
The first freeze in the immediate metro St. Louis area is usually delayed due to the urban heat island. This tends to keep temperatures a touch warmer. In the immediate metro, during most years, the first freeze will not happen until the first week of November. A hard freeze, defined as a low temperature of 28 degrees or colder, occurs in most of our region during the very end of October in the colder locations and in the month of November elsewhere.
The current thinking is October will be above average temperature-wise overall. There most likely will be two or three cool snaps through an otherwise relatively warm month.
Download the free 5 On Your Side app to get the latest watches and warnings and track conditions live with our interactive radar. Use the links below to download now.
5 On Your Side news app
iPhone | Google Play