After two months of rain, Juneau residents are rejoicing in blue skies, but spring and summer rain remain critical in preventing drought.
Southeast Alaska had an unseasonably wet spring due to a persistent low-pressure area over the Bering Sea. According to the National Weather Service Juneau, Southeast saw measurable rain (greater than 0.01 inch per day) for 30 days in May and received two to four times the average rainfall for the month.
Juneau received 6.46 inches of precipitation in May, well above the historical average of 3.51 inches but short of the record 9.2 inches that fell in 1992, according to the weather service. Record precipitation for May was recorded in Ketchikan, Petersburg, Skagway, Haines and other communities.
These especially rainy conditions arrived after a winter of very low snowpack. Snowpack is crucial to the region’s hydrology, providing a steady supply of meltwater to keep lakes full throughout the summer. However, due to relatively dry conditions and freezing temperatures at higher elevations, little snowpack formed in the mountains of Southeast this winter, raising concerns about drought later in the summer.
“If the rains don’t continue through the summer, then we would anticipate that we could see the development of drought conditions in Southeast,” said Brian Brettschneider, senior climate scientist with the National Weather Service Alaska Region. “But as it stands now, all drought concerns have been eliminated.”
Increased precipitation in the spring is notable, as May and April are historically drier and sunnier in Southeast Alaska. For most months, daily average precipitation has increased over the last 85 years in Southeast, Brettschneider said. April and October are exceptions, trending drier.
“Spring 2025 is just kind of a wild outlier,” he said. “It’s really, really wet and it’s not part of any kind of long-term trend in the spring season.”
The unusually rainy weather over the past two months was caused by a persistent upper-level elongated area of low pressure (or “trough”) over the Bering Sea. This resulted in surface-level low pressure over Southcentral Alaska and the Gulf of Alaska. As air converges on a low-pressure area, it uplifts and condenses, forming clouds and ultimately rain.
In the past two months, Southeast Alaska has been in the path of atmospheric rivers, long, narrow regions of atmospheric moisture moving toward this persistent low-pressure zone. The region encounters these atmospheric rivers after they have traveled thousands of miles over the Pacific Ocean and absorbed significant moisture.
“Not an unusual combination of things, but the persistence was unusual,” Brettschneider said.
According to a paper published in The Journal of Geophysical Research in 2024, heavy precipitation caused by atmospheric rivers contributes to landslides in Southeast Alaska.
“We had a few documented landslides reported in populated areas over the last few weeks, including one 5 miles north of downtown Ketchikan that impacted 1 property & one in the Metlakatla area on Annette Island, along with a couple of other minor slides that didn’t impact any properties,” Lance Chambers, lead meteorologist at the National Weather Service Forecast Office in Juneau said in an email to the Juneau Empire on Sunday.
As the low-pressure trough over the Bering Sea dissipated, Juneau saw some sunnier, drier days.
“That regime is being replaced,” Brettschneider said. “It’s being moved out with high pressure around the Alaska Peninsula. It’s generating kind of a westerly and northwesterly flow.”
Unlike the predominant atmospheric rivers of the last two months, a flow traveling from the northwest will encounter Southeast Alaska after traveling over land, accumulating less moisture.
“Could it be?! A couple days with little to no rain?!” Even the National Weather Service Juneau sounded hopeful in its Sunday afternoon post on Facebook.
• Contact Natalie Buttner at natalie.buttner@juneauempire.com.
