It might seem a little early to start the summer 2023 review, but in addition to there being several posts worth of climate information to digest, summer in the North starts to wind down early compared to the mid-latitudes. This is principally because of the rapidly decreasing solar heating in August. On August 21, two months after solstice, total solar heating at 65°N (Nome, Fairbanks, Norman Wells, NWT) has decreased by 34 percent from the solstice peak. For comparison, at 40°N (Philadelphia, Springfield, IL, Boulder CO), solar heating has declined only 15 percent from the solstice. The drop of temperature is most dramatic away from the moderating influence of the oceans and is a principle reason way August is rarely or never the warmest month of the summer in Interior Alaska and much of the Yukon Territory and NWT. As you might expect, temperature are somewhat modulated in areas close to the coast by the lag in ocean surface temperature, which typically peak in late July or early August, except mid-August to early September southern Bering Sea and in the north right near the sea ice edge.
Highest Temperatures 2023
Figure 1 shows the highest temperature reported during the 2023 summer (May through August). It is possible, albeit unlikely, that higher temperatures could occur in the next couple of weeks on the Bering Sea or western Gulf of Alaska coasts.
From the climate perspective the single highest temperature over the summer is less important than longer duration temperatures extremes, but it’s certainly something that grabs folks attention. Southcentral and southwest Alaska summer highs were notably cool. Anchorage Airport high temperature of 73F (22.8C) and Bethel 76F (24.4C) are the lowest summer highs since 2011, and Kodiak’s 75F (23.9C) is the lowest since 2012. In contrast, the highest temperature on the North Slope were close to all-time records, and all-time records were set July 7 and 8th at a few places in the Yukon Territory and especially the lower and middle Mackenzie River valley in the Northwest Territories (my post about this historic event here). Unusually, the warmest weather for some places on the outer coast of Southeast Alaska occurred very early in the season, when on May 18th Sitka Airport tied the monthly record high of 82F (27.8C) and Klawock’s high of 86F (30.0C) turned out to be the only daily high temperature in the 80s for the entire summer.
Northern Wildfire
Late July and early August brought ideal weather for late season wildfire. The mid-atmosphere flow pattern shown in figure 3 produced unprecedented thunderstorm activity for so late in the season over parts of Alaska and the Yukon Territory. To the east of the high pressure center, very warm and mostly dry weather continued across the Northwest Territories.
Wildfires are still burning in northern North America but growth has slowed significantly due to more seasonable weather in most areas. With nearly 2.4 million hectares (5.9 million acres) burned, 2023 is the largest wildfire season in northern North America since 2015 and is the largest area burned in the Northwest Territories since 2014. Of course, the evacuation of nearly the entire population of the Yellowknife, NWT area in mid-August underscores the potential threat of wildfires on the ground when combined with dry fuels, and in the southern NWT fires are still growing. Figure 3 shows the annual area burned in the three regions since 1988.
However, since August 10th evacuation alerts have been downgraded or lifted in many areas, including the Anderson area near the Parks Highway north of Denali National Park, the Haystack subdivision north of Fairbanks, Old Crow, YT and Inuvik, NWT. In Alaska, as of August 19 there were still eight staffed fires, down from 15 the first week of the month. However, it’s likely to be a different story in northwest Canada, where some wildfires are likely to putter along until the snow comes, and even then there will be the risk of so called “zombie fires” reappearing in the Spring 2024 from fires that smoldered in the duff through the winter.