January Climate Data

Last month was the wettest January statewide in Alaska since at least 1925, according to NOAA's monthly climate data released today.  The previous record holder was January 1949.

Interestingly, none of Alaska's individual climate divisions was record wettest, and that's largely because January 1937 was even more extreme for large parts of the state; but January 1937 was also very dry in (typically wet) southeast Alaska, so it only ranks as (now) 5th wettest statewide.  Compare the two rank maps below:

Here's a map of the difference in absolute precipitation amounts:

As noted in blog posts about the late January storm, some of the precipitation fell as rain as far inland as the Yukon Flats, and with few reliable ground-truth measurements, it's difficult to assess how much snow fell.  No doubt it was "a lot" in areas that dodged the rain and weren't affected by downslope "rain shadow" effects; ERA5 data shows a large area with over 3 times normal liquid equivalent snowfall.  Rick Thoman reports that the highest measured total accumulation was 53" at Wiseman.

The NRCS snowpack map for the end of January shows most of the interior monitored basins in very good shape, but snowpack remained much below normal on the Kenai Peninsula and in Southeast.

ERA5 estimates from a week ago also show widespread ample snowpack for the northern interior and the southern slopes of the Brooks Range, but that's a big contrast from little or no snow for the western Seward Peninsula (if the model is to be believed), the west side of the Alaska Range down to the Alaska Peninsula, and south-central valley areas.

January 2025 was also a very warm month statewide, as we would expect in a wet and cloudy pattern: the correlation between precipitation and temperature is significantly positive in winter, the opposite of summer.  Compared to the last 30 years, the most anomalously warm region was the northeast, where only 2016 was warmer in recent decades.  NOAA/NCEI says that both January 1981 (by some margin) and January 1937 were warmer than January 2016 on the North Slope, although that isn't true at Utqiaġvik.

As for wind, it was a windy month in the vast majority of areas outside of the Panhandle.

The mid-atmosphere flow pattern responsible for all this was anchored by an unusually strong ridge over the northeastern Pacific.  There was also a trough axis over far eastern Russia, and the persistent southwesterly flow between these two features is what transported the warmth and moisture into Alaska.

The position and orientation of the ridge is very similar to what occurred in January 1949, previously the wettest January on record for the state:

Just like in December, the January pattern was very different from the classical La Niña pattern, which involves a trough over western Canada and a ridge over the Aleutians.  Here's the average 500mb height anomaly for 10 years with strong La Niña conditions in January (La Niña is not particularly strong this winter, but this illustrates the point):

With both December and January being top-10 warm months, there's a chance this could be Alaska's warmest winter (Dec-Feb) on record - but only if February ends up in the top 8.  The next week looks more seasonable, so it seems unlikely, but I wouldn't rule it out.