In hindsight, the switch was thrown on Aug. 11.
In the first 11 days of August, the high temperature was no lower than 67 degrees. One day topped 80 degrees. Nine topped 70 degrees. Only one one-hundredth of an inch of rain fell at the airport, Juneau’s official measuring point.
Then, the switch was thrown: August 2017 finished as the 12th wettest August since accurate records began at the airport.
Starting Aug. 11, it rained for 18 consecutive days and 20 of 21 August days after that point, according to the National Weather Service office here.
Creeks and rivers are running high, and both Mendenhall Lake and Mendenhall River neared minor flood stage on the first day of September.
In total, 8.46 inches of rain fell on Juneau in August, the last month before the official start of the rainy season.
August is the last month of climatological summer, and on the first day of September, the yellowing foliage was apparent with a close look.
In Juneau, it’s been a cool and damp year overall. Since the start of the year, Juneau has had 41.53 inches of precipitation (rain and melted snow). In a normal year, Juneau has 33.17 inches of precipitation by this point.
This summer, Juneau had only 13 70-degree days; in a normal year, it has 19. (There hasn’t been a 70-degree day in September since 2010.)
There was one lonely 80-degree day this summer: It reached 81 degrees on Aug. 5. In a normal summer, Juneau averages two 80-degree days.
Climatological fall (September through November) is Juneau’s wettest month of the year, and the National Weather Service’s Climate Prediction Center is leaning toward a wetter-than-normal September. Its three-month forecast indicates there’s an equal chance of above-normal, below-normal or normal rainfall for the season.
In the short term, local forecasters are predicting a weekend break in the weather, with partly sunny conditions on Saturday afternoon and Sunday before the rain returns in time for the workweek.