Wednesday, March 17, 2021

Chilly Late Winter

After a relatively warm start to winter (see this post from early January), the last six weeks have been on the colder side of normal in much of Alaska.  February was the coldest since 1999 in Fairbanks and Anchorage, and up north it was colder still; for example, it was the coldest February since 1990 in Bettles.  Here's Rick Thoman's excellent summary graphic:

March has also been somewhat colder than normal, and a cold spell late last week brought considerable discomfort to the Iditarod teams.  Fairbanks reached -35°F for two nights in a row, and a number of spots dropped below -40°F, including -44°F at the Salcha RAWS.  Here's a map from Friday morning, with temperatures in red:

When all is said and done, the extended winter period will end up near normal for temperature in many locations.  Here's the daily chart for Fairbanks: near normal to begin the winter, persistently warm in December and most of January, and generally colder than normal since then.

As I noted in the January post, the surprise in all this is that the robust La Niña episode didn't prevent a long period of anomalous warmth in the heart of winter.  This is related to the fact that the Arctic Oscillation was strongly negative from mid-December to mid-February; the negative AO phase produces cold over Eurasia and the lower 48 states of the US, but northern North America tends to be warm (see below).  However, the AO is typically positive, not negative, during La Niña winters; so a lot of ENSO-based long-range forecasts went awry this winter.

For completeness, here's Rick's temperature graphic for January.


  1. Winter lingers in Fairbanks. Being cold with snow plus increasing daylight can make some irritable...we'd like to go out more and enjoy the sun and Spring.

    But most would probably trade our current weather for the relatively mild mid-winter during December and January we just experienced. Any minor cold now would have been magnified during those dark days.


    1. I never fail to be amazed at how long it takes for the sun to drag the north out of winter. Light yes, warm no.

  2. Really like your site and ongoing analyses of the weather up here. I live in the foothills of the Alaska Range, North side, and the weather is extremely variable from year to year. So astounding to me when March rolls around with the longer, brighter days and soon hoped for return of spring, yet it still is way below zero at night (23 below the night before our spring equinox!) and there is a good 4-5 feet of snow in the woods! It seems unfathomable right now that all this will melt and we aren't headed into another Ice Age, but I know I have felt this way just about every year at this time.

    1. Thanks for reading, and I'm glad you enjoy the blog.

      I'm curious if snowpack seems greater than normal for your location this year?