From a basic climate perspective, June in most of Alaska was not an exceptional month. Southern Alaska was on the wet and cool side, but not dramatically so, while much of the central Interior was drier than normal with monthly temperatures close to average. More on that in a coming post. However, that’s only part of the climate story.
June sea ice melt was relatively slow around Alaska. A small amount of ice persisted unusually far south in the central Bering Sea, near St. Matthew Island, until mid-month and ice cleared the Bering Strait after June 20th. In the Chukchi Sea, ice along the northern Seward Peninsula coast and Kotzebue Sound cleared about the same point in the season or slightly earlier than in 2022. However, even by month’s end there was not a sustained open water passage to Point Barrow (the northernmost land in Alaska). On the other hand, the southeast Beaufort Sea had considerably more melt this June than in 2022, in part spurred on by the very warm weather and comparatively warm MacKenzie River water discharge. Figure 1 shows the June median daily ice concentration from the high resolution AMSR-2 passive microwave data.
In the Chukchi Sea, overall melt in June was the least since 2012. The daily open water extent averaged only about 8 percent of the Chukchi Sea basin (as defined by the National Snow and Ice Data Center). Figure 2 plots the 1979-2023 time series of June open water extent, and as you can see this June would have been typical in the 1980s but was far below the recent years average. In fact, this was the lowest June average since 2006, though very close to June 2012 and 2013.
Wildfire
No doubt the most remarkable feature of the June 2023 Alaska climate was the very low wildfire activity. In June only 934 acres (378 ha) burned in Alaska, which is less than 1 percent of the 1993-2022 median. That brought the 2023 seasonal total area to only 1332 acres (539 ha). Both of these are far and away the lowest for June and to this point in the season in the 31 years we have (near) daily estimates of area burned. Beyond that, this may be slowest start to the wildfire season since 1978 or 1965, when the total area burned in each of those years for the entire season was less than 8000 acres (3200 ha). To the east of Alaska, wildfire activity was also very low in the Yukon Territory, with only 5100 acres (2064 ha) burned through the end of June. In contrast, the Northwest Territories had burned 1.50 million acres (608995 ha) at the end of June but with limited increase during the last ten days of the month.
The reasons for the exceptionally slow season are primarily a lack of thunderstorms to provide wildfire ignitions and and an absence of sustained warm dry weather to allow fires time to grow. From May 15 through June 30 there were about 13,000 lightning strikes detected in a Alaska. To put that in perspective, summers 2013, 2015, 2016, 2017, 2019 and 2022 all had one or more days with more 13,000 strikes. The mid-May through June strike totals are shown in Fig. 4. This year’s total through June 30th is less than half of the next lowest year (of this very short time series).