Can you feel it in the air? The seasonal chill that signals the first fall frost and freeze usually arrives by the second half of October through the first few days of November.
Average First Fall Freeze
On average, morning temperatures plummet to the low 30s sometime around October 17 through 20 for Fayetteville as well as Valley Head.
About one week later, freezing temperatures usually occur from Russellville to Moulton south to Cullman, as well as Decatur to Scottsboro as well as Winchester. These areas tend to see their first freeze around October 25 through October 28.
Southern DeKalb County — including Crossville — tends to see their first fall freeze just before Halloween (October 30).
Huntsville and the Shoals tend to see their first fall freeze shortly after Halloween (November 1-2).
Areas of Marshall County near Lake Guntersville tend to remain more moderated due to the specific heat contained within the lake water; as a result, air temperatures tend to not reach the freezing mark until near the second week of November.
Average First Fall Frost
The average first fall frost dates for the Tennessee Valley fluctuate compared to the first fall freeze, but they are roughly the same date if not a week or two later.
What’s the difference between a fall frost and a fall freeze?
Both the terms “frost” and “freeze” imply temperatures in the 30s, but the difference between the two terms has to do with the amount of moisture that is in the atmosphere.
A “frost” means that not only will air temperatures drop to the 30s, but that the dewpoint will also be at or below freezing. The dewpoint is the temperature at which any (gaseous) water vapor in the air condenses, and in the case of frost, the water vapor goes from gaseous form to frozen form. This type of frost creates the dendritic look on windshields and windows.
Frost can also happen when dew forms on grassy or cold metal surfaces, and then freezes when the air and water temperatures drop below freezing. This type of frost produces almost a glaze on windshields and windows.