November 2017 Climate Stats


November`s average of 43.8 degrees is the tenth warmest at the Boise Airport. Aside from a cool spell from the 4th through the 8th, temperatures averaged above normal on most days. Only ten nights had lows were below freezing. The low of 47 on the 22nd set a record high minimum for that date, eclipsing the old record of 46 set in 1921.

Measurable rain fell on half the days. The monthly total of 1.77 inches is nearly half an inch above normal and ranks among the wettest 25 percent of Novembers at the airport.

Typical of fall, the weather pattern was active, with passing weather systems bringing showery periods and changeable temperatures.

On the 3rd, a low pressure trough from British Columbia brought Boise the coolest weather since last winter, and over half an inch of rain from the 3rd through the 6th. Below normal temperatures persisted through the 8th. The low of 25 on the 7th was the low for the month and the coldest reading since February 25.

Warmer more seasonable weather returned on the 9th. A weak high pressure ridge over the western U.S. and a persistent low pressure trough off the northwest coast kept us under southwest flow aloft, maintaining near normal or slightly above normal temperatures through the 20th.

Weather disturbances moving inland weakened as they traversed the ridge, but they retained enough moisture for moderate amounts of rain on the 10th, and again on the 14th and 15th.

On the 21st an unseasonably warm high pressure ridge built over the Desert Southwest and northwest Mexico, creating a source of warm air for the northern intermountain region. From the 20th through the

27th, Boise’s daily average temperatures ranged from 6 to 19 degrees above normal.

Moisture and weak weather systems moving through the north portion of the ridge generated nearly daily showers as far south as northern Nevada. Amounts were mostly light, but a stronger disturbance on the 24th produced a quarter inch of rain at the Boise airport.

The ridge weakened following a Pacific weather system which crossed the great basin the 27th, and temperatures at Boise returned to near normal on the 29th following a Pacific cold front.

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