First Frost Potential

To get the first frost of the season to occur this early, it requires not only a cold air mass, but also a clear sky and very light wind.   Plus, early season frost also occur when the soil is dry, as that helps in the radiational cooling process.  A couple of weeks ago, I mention that the first air mass I thought may be cool enough for a frost would occur toward the middle of September and at the moment it appears that the mornings of September 13 and 14 would have the potential for temperatures to drop into the low to mid 30s especially in northern North Dakota.  But wet soils there may help, plus, a cloudy night is 10 degrees warmer than a clear night, meaning potential doesn’t necessarily equate to occurrence.