Alaska's Incredible Winter Warmth
January 2025: storm after storm and atmospheric rivers
January 2025 was a very mild month for nearly all of Alaska. I’ll have the monthly recap once the complete ERA5 reanalysis becomes available.
The start and end of the month were cold in many areas, but in between, most of mainland Alaska saw very mild weather: dozens of daily records were set in all parts of the state and, in some cases, new monthly or seasonal records were established. This long post brings together some of these extremes, but this is nowhere near comprehensive.
Overview
Figure 1 shows the Alaska statewide temperature index developed by Brian Brettschneider and myself some years ago to assist in answering questions like “has it been warm in Alaska lately?” in near-real time. The index is not temperature departure. Rather, it’s a standardized difference from normal confined to a range between -10 and +10 in order to accommodate the radically different climates and seasonal variability in Alaska.1 The index was very high January 10-13 and then again January 18-25. In January, 12 days had an index value above +9, the most such days in any month since March 2019.
January 10-13, 2025
A series of strong storms moved through the eastern Bering Sea, bringing rain and snow to many areas not protected by cross-mountain flow aloft. In the Tanana valley it was a classic Alaska Range chinook as south winds aloft crossing the high terrain were warmed through the moisture loss on the windward side of the mountains. Figure 2 plots selected high temperatures for January 12 in and around the state.2 At Fairbanks airport, the high temperature of 47F (8.3C) on the 12th was the highest January temperature since 2009, and 53F (11.7C) at Nenana was 1°F from the highest January temperature on record and, based on reports available so far, the highest reliable temperature outside of Southeast in January: Sitka airport will likely have the highest temperature in the state in January at 54F (12.2C), but this is not unusual.
January 17-19, 2025
The weather situation here was a little different. Yet another storm moved from the North Pacific, bringing widespread rain and snow in western Alaska, including blizzard conditions at Kotzebue. But this time there was strong high pressure over eastern Interior Alaska and the Yukon Territory. This protected the central and eastern mainland from as strong a chinook as a few days before, but in the north there was enhanced cross-Brooks Range flow. As a result temperatures rose to near or above freezing over most of the North Slope. The high of 41F (5.0C) at Umiat ties the record for the month there set in 2008.
January 23-27, 2025
The extremes in the fourth week of the month were in many ways the most remarkable of the month. The meteorological set-up was very different from earlier in the month. In this case, an atmospheric river set up between strong higher pressure west of the British Columbia coast and modest low pressure south of eastern Aleutians. As a result, subtropical air poured north into southwest Alaska and then made the turn to the northeast. The flow and moisture pattern on the afternoon of the 24th (as seen in Fig. 4) only evolved slowly over the following couple of days as the high weakened and the core of the moisture feed drifted east. The push of warm air brought rain as far north as the northwest North Slope, copious rain in southwest Alaska and extended period of unseasonably mild weather. In the Anchorage area, the already meager low elevation snowpack was melted out by more rain and the extended warmth, resulting in the first “bare ground in January” since 2016 and the first “bare ground in late January” since 1983.
Temperatures
There were a number of new January record high temperatures established January 24-27. Tanana has more than 120 years of climate observations, and the high temperature of 43F (6.1C) on January 24 broke the previous January record of 41F (5.0C). Old Crow, in the northern Yukon Territory also set a January record with a high of 38F (3.2). In the Southeast Interior, the NWS cooperative station at Tok reported 47F (8.3C) on January 25 followed by 49F (9.4C) the following day. Tok has been an NWS cooperative station since the 1950s, and the January 26th high of 49F is the highest temperature any date between November 2 and March 10.
Possibly more remarkable was the continuous nature of the very mild temperatures, reflecting the subtropical origin of the airmass, and as a result a number of record high minimums for January were set on the 25th. These included 44F (6.7C) at Kodiak, 43F (6.1C) at King Salmon, Ft. Greely/Delta Junction 41F (5.0C), 38F (3.3C) at Anchorage and 33F (0.6C) at North Pole. Fairbanks airport low temperatures of 33F (0.6C) on January 25 was only the second January day in 120 years of climate observations to have a low temperature above freezing. Possibly the most remarkable occurrence was the low temperature at Tok on January 26 of 39F (3.9C). This is the highest daily low temperature at Tok any date between October 17 and April 21.
Anchorage airport reported a temperature above freezing for 119 consecutive hours, Ft. Greely near Delta Junction 95 hours and Fairbanks Airport remained above freezing 61 consecutive hours. All are January records.
Figure 6, courtesy B. Brettschneider, shows the ERA5 January 24 average temperature departure from the 1991-2020 baseline. Notice the scale: all the red shades are more than 35°F (19°C) above normal. For Alaska overall, the average temperature of 26.37F (-3.13C) was third highest for any January day since 1950, with only January 21, 1961 and January 24, 2014 higher.
Precipitation
The atmospheric river also produced a winter rain event in the central and northeast and excessive precipitation in parts of southcentral and southwest Alaska.
In the Fairbanks area, the airport reported 0.13 inches (3.3mm) of rain in the morning and early afternoon of January 24, and there was occasional light rain the following days. Significantly higher amounts of rain were measured elsewhere in the immediate Fairbanks area, including 0.30 inches (7.6mm) at UAF West Ridge and 0.34 inches (8.6mm) at the Goldstream Creek cooperative station. Many schools and businesses closed or significantly curtailed activities on account of the rain, and this was the largest rain event in January in Fairbanks since 2013. Perhaps even more remarkably, Fort Yukon, on the Yukon Flats in the northeast Interior, reported 0.11 inches (2.8mm) of rain with the temperature above freezing on January 24. Any rain in this part of Alaska in winter is very rare. There have been a few occurrences of rain in January with sub-freezing temperatures, but while Fort Yukon does not have a robust historical weather or climate dataset, this may have been the first rain and above freezing temperatures since January 1962.
Extreme multi-day precipitation totals, either rain or mixed rain and snow were widely reported in parts of southcentral and southwest Alaska. In the Talkeetna area, 3-day total precipitation amounts of 4 to 5 inches (100-125mm) were reported from multiple CoCoRaHS observers and the NRCS SNOTel.3 The higher elevation Independence Mine and Frostbite Bottom SNOTels in the mountains north of Palmer reported similar precipitation totals. Tokositna SNOTel, located north of Peterville but at valley elevation reported close to 10 inches (250mm) of precipitation but with only about a 12 inch (30cm) increase in snow depth.
In southwest Alaska there is much less in-situ data, but what there is paints a similar picture. The NOAA climate reference network station at Aleknagik reported 5.5 inches of precipitation, most or all of that rain, January 23-26. The lower Kuskokwim River area, which had been a “snow drought” through mid-January received heavy snow as the moisture-laden air overran colder air near the surface. Bethel’s total precipitation January 23-26 of 1.84 inches (46.7mm), the highest 4-day total in January since 1933 and fifth highest (non-overlapping) 4-day total during winter in Bethel's 100 years of climate observations. The NRCS SNOTel at McGrath reported 3.8 inches of precipitation but with only about a 10 inch (25cm) increase in snow depth (NWS automated observation did not report online most of the storm, likely due to prolonged power outage).
Technical Details
Most climate records extracted from the xmACIS website, here.
Ogimet, link here, is a useful “one-stop shop” for internationally shared meteorological data.
PolarWx, link here, run by Tomer Burg, has many useful weather model related plots.
ERA5 data is available here and NRCS SNOTel data available here.
I post these high temperature maps on most days when I’m not traveling on my Mastodon (@AlaskaWx@alaskan.soical) and BlueSky (@alaskawx.bsky.social) accounts.
The NWS automated observation at the Talkeetna airport failed, possibly due to power outage, and there is no back-up.
Very interesting Rick.
This year it has been cold in the U.S. Southeast. Reminds me of 1976/77 when, if I recall correctly, Fairbanks seasonal min temp that winter was warmer than Cincinnati's until late in the winter when Fairbanks temps did drop off finally & ended up colder than at Cincinnati.
"Many schools and businesses closed or significantly curtailed activities on account of the rain..."
It dawns on me that a reader from the Lower 48, or even southern Alaska, might wonder why rain and warmth would cause closures. My childhood memories of such events in New England are of a lot of miserable slush, and waterlogged shoes and jackets. But in Fairbanks it's downright dangerous, especially where hills are concerned.