"In the past four days," the National Weather Service says, "we have gone from fall right into winter."

It was 40 below in Huslia this morning. Lows tonight and Tuesday  night in Fairbanks are expected to be in the 15 below to 35 below range, with the coldest readings in the rural valleys.

Temperatures are expected to warm up a bit by the weekend, with highs of 5 below and lows of 20 below.

For Fairbanks, low temperatures in the 30  below to 40 below range at this time of year are classified as "very cold," according to an informal table that forecasters compiled here a few decades ago. 

"Extremely cold" kicks in at 40 below during November, a label that is reserved for readings colder than 50 below in December.