The First 36 Degree Low

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.

 

36 lows
First 36° reading of Autumn. Click to enlarge

Daryl Ritchison