ST. LOUIS – Fall-like temperatures are starting to settle in to the St. Louis region. Before too long, St. Louis may also experience its first freeze of the season.
The freezing point, a crisp 32 degrees Fahrenheit, hasn’t arrived just yet. Temperatures are not expected to dip that low through at least next week, with FOX 2’s latest seven-day forecast forecasting low temps in the high 40s. Still, the season’s first freeze could be sneaking up sooner than you think.
According to Climatology Data from the National Weather Service, St. Louis should anticipate its first freeze of the fall season around November 2.
That is the average date of the first fall freeze in the City of St. Louis between 1991 and 2020.
Climatology data also shows the following trends for St. Louis…
The earliest fall freeze on record is October 7.
The latest fall freeze on record is November 27.
The average first frost is October 23.
The average first hard freeze November 15.
There are some differences between “frost” and “hard freeze” from the typical “freeze,” though all could pose dangers to plants and vegetation to certain extents.
Frost can occur when temperatures dip between 32 and 36 degrees Fahrenheit, just above the freezing point. Frost could develop even if the air temperature is above freezing as long as surface temperatures cool enough for moisture to freeze.
A freeze occurs when temperatures fall below 32 Fahrenheit for an extended period of time. A deep freeze occurs when temperatures fall below 28 Fahrenheit or lower for several hours.
The closer to the freezing point that temperatures fluctuate, the more likely sensitive plants, flowers and hard crops could be damaged. To protect plants from the inevitable, experts recommend bringing potted plants indoors or investing in a frost fabric cover or blanket for plants that stay outdoors.
Meanwhile, the National Weather Service reports the following first fall freeze averages for cities around the St. Louis metropolitan area…
Belleville, Illinois: October 14
Chesterfield, Missouri: October 19
Cahokia, Illinois: October 21
Farmington, Missouri: October 18
St. Charles, Missouri: October 22
One NWS worker explained to FOX 2 over the phone that some parts of the St. Louis region may experience freezes earlier than the city due to various environmental factors. For instance, Chesterfield’s NWS system is located near a river valley that typically gets colder in the evening hours compared to a more urbanized area like the City of St. Louis, thus more likely to fall to freezing temperatures in the evening.
