The remainder of October is trending colder. Even colder air could come in as early as next weekend. There is a slight threat for patchy frost in Northwest Arkansas Monday morning, October 15th. (Possible Tuesday morning, October 16th too)
Average First Frost – Fayetteville: October 19th
Average First Frost – Fort Smith: November 5th
Patchy Frost: 38-42°F
Frost: 33-37°F
Widespread Hard Frost/Freeze: 32°F or below
(The reason why? These air temperatures are estimated 2 meters above the ground. It can actually be a handful of degrees colder at the grass and plant level.)
WHAT YOU NEED TO CREATE FROST:
- Cool Temperatures: The air around plants needs to be around the freezing mark, as well as the dew point.
- Clear Skies: Clouds act like a blanket at night. Clear skies will allow temperatures to drop more quickly.
- Little-To-No-Wind: Winds mix the air too much to produce frost. Even with north winds, turbulent eddies near the ground will prevent a delicate frost from forming.
- Valleys: Valleys can get colder than the tops of hills thanks to negative buoyancy. Cold air from the tops of terrain sink into valleys at night. The best chance to see a frost when the forecast is borderline is in low-lying areas.
As of right now, it will not be cold enough in the River Valley to produce frost next week.
-Matt
