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.