With much cooler temperatures expected to arrive this week, there is certainly a risk that some parts of the region will record the first freezing temperature of the season. More likely than the first 32° of this season in many locations will instead be the first 36° temperature. 36° is sometimes considered a “frost” as the official temperature is measured in the 4 to 6 foot range and often frost can be observed at that temperature at lower heights and objects (roofs, metal, etc) may drop to 32° under those circumstances.
The average first 36° day in North Dakota is in the September 10 to September 15 time period. Actual dates at select locations around the state are listed below:
Ashley September 5
Bismarck September 12
Dickinson September 1
Fargo September 14
Grand Forks September 12
Langdon September 1
Minot September 8
Williston September 11
Therefore, if temperatures dropped to 36° at these locations it would occur very close to the long-term average. The actual date of the first 36° of the season in Fargo are presented in the graphic below. Of interest is there has been no trend in the first 36° at this location since 1900. Considering the urban build up in Fargo Moorhead that is notable.
Daryl Ritchison