In Alaska, a summer of extreme weather continues

Alaska is having a rough summer. Following a July that was Alaska's hottest month on record, erratic and unusual precipitation totals have caused downpours in some parts of the state and sparked fires and water restrictions in others.

August and September are typically the wettest months for Alaska. Northern Alaska, including Fairbanks, has been inundated with precipitation this month due to an atmospheric river event. Meanwhile in Southern Alaska, Anchorage received only trace amounts of rain in August, and only a quarter-inch of rain fell on Ketchikan, where water restrictions were being enforced until a heavy rain event Wednesday.

[This summer is on track to be the driest on record for Southcentral Alaska]

This lack of precipitation is also contributing to wildfires. Alaska’s fire season typically ends in July with the onset of August precipitation, but last weekend, dry conditions and high winds sparked a new fire, the McKinley Fire, just north of Anchorage along Parks Highway, destroying about 50 structures. These conditions also ramped up the already existing Swan Lake Fire in the Kenai Peninsula that was mostly contained, spreading smoke across Anchorage and a large swath of South-central Alaska. In Anchorage, air quality has been among the poorest observed in the United States this summer.

"In most years, the season really ramps up around the first of June and reliably dies down by the first of August. Occasionally, the fire season lasts well into August." according to Brian Brettschneider, a researcher for the University of Alaska at Fairbanks at the International Arctic Research Center. While in the Lower 48 it can take months for vegetation to dry out enough to fuel fires, in Alaska, black spruce forests can be susceptible to fires after only a few days of dry conditions.

This is not a record fire year for Alaska, but it is a significant one with more than 2 million acres burned. The amount of acres burned due to wildfires throughout Alaska’s recorded fire history is variable, however the frequency of fire seasons where 2 million acres or more are burned has increased in recent years.

The setup for this extended fire season was exacerbated by unusually warm temperatures early in the summer. Anomalous warmth in the past year, as well as warmer-than-usual waters in the surrounding Bering, Chukchi, and Beaufort seas and the North Pacific Ocean fueled the warm and humid conditions experienced by Alaskans.

This "bathtub" of warm water surrounding Alaska helped contribute to higher-than-normal temperatures, especially overnight lows that trended higher than normal. In Anchorage, June and July were the warmest months ever recorded, with nighttime lows that rarely dropped below 50 degrees for most of the summer. In a city with buildings designed to keep warmth in, this has been problematic for residents.

Anchorage has seen 14 nights drop below 50 degrees this summer. The only other time the city saw so few was in 2016, when they had only 13 such nights. From 1952 to 2012, Anchorage had only five nights that failed to drop below 60 degrees. This summer, they have had 18 of those nights.

The warmer-than-usual waters are not expected to cool anytime soon, which will likely lead to a milder fall and early winter period. Alaskan firefighters who normally transition to firefighting in the Lower 48 in August continue to battle the fires back home.

About this story

Precipitation data from National Weather Service. Satellite imagery from NASA Worldview. Fire history data sourced from the Alaska Interagency Coordination Center and the Alaska Forestry Service. Sea surface temperature anomaly data from NOAA. Anchorage daily temperature data from National Weather Service.