Flood — Matanuska Valley, Alaska

2025-06-22 to 2025-06-30 · near Sutton, Matanuska Valley, Alaska

Event narrative

After a cool start to the month of June, Palmer quickly warmed up June 10 through 21, 2025. In this timeframe, the Palmer airport reported six days of 70 or above temperatures with a high of 75 on June 19th. This reflects a warm and dry pattern that set up region-wide and enhanced snowmelt in the headwaters of the Matanuska River. Further, only .02 inches of rain fell at Palmer from June 10-21. Warm temperatures and bank erosion led to high water breaking through the banks of the Matanuska River (noted at the Matanuska River Bridge (MATA2) gage) between the Old Glenn Highway and the River in the Maud Road area due to flooding caused by snowmelt and a river channel shift.

Reports indicate that due to this flooding, five homes and two businesses were damaged, and $1 million plus in road damage was noted. This led to a local disaster declaration.

News articles:

https://www.alaskasnewssource.com/2025/06/23/matanuska-river-flooding-crew-works-emergency-protective-measures/.

https://www.alaskasnewssource.com/2025/06/25/matanuska-river-flooding-leaves-river-running-through-properties/.

Wider weather episode

After a cool start to the month of June which slowed the melting of the mountain snowpack, Palmer quickly warmed up from June 10 through 21, 2025. In this timeframe, the Palmer airport reported six days of 70F or above temperatures with a high of 75F on June 19th. This reflects a warm and dry pattern that set up region-wide which enhanced snowmelt in the headwaters of the Matanuska River. Only 0.02 inches of rain fell at Palmer from June 10-21, but the warm weather caused rapid snowmelt and increased river flow as measured at the Matanuska River bridge (MATA2 Gage) in downtown Palmer during this period.

Weather throughout the region prior to the flooding of the Matanuska River featured a rapid change from cool and wet to warm and dry. Temperature measurements at the Palmer Airport indicate average temperature departures of up to 7.8F below normal from June 1 to June 10 followed by a rapid increase in temperatures up to 4.8 degrees above normal from June 12 to June 21. Perhaps what is most notable, and the reason for rapid river rises along the Matanuska River, is the change in the alpine environment during this time period. For analysis, the Marmot Peak weather station located at 4,500 ft and the Independence Mine Snow Telemetry Site (SNOTEL) at 3,450 ft, both located in Hatcher Pass, will be used as proxy stations for the alpine and snow environment for the Matanuska River drainage. These stations are the only ones available in the region at representative elevations, and while neither of these stations directly influence the Matanuska River drainage, conditions were likely very similar.

Temperature data from the Marmot Peak weather station shows temperatures between June 1 and June 10 ranging from 26.1F to 39.9F with an average of 31.5F. From June 11 to June 21, temperatures rose to between 35.6F and 61.9F with an average of 47.3F. Analysis of the snow water equivalent shows little to no snow melt from June 1 to June 10 with multiple days of snow accumulation and a liquid equivalent increase up to 1 inch measured from June 6 to June 8. This was followed by a loss of 17.2 inches of liquid equivalent between June 10 and June 24. High resolution satellite imagery captured by the Sentinel-2 polar orbiting satellite shows a rapid reduction in high-elevation snowpack surrounding the greater Palmer area and Lower Matanuska Valley. Similar satellite imagery shows an altered river state from June 12 to June 20.

View location on OpenStreetMap → (61.6856, -149.0787)

Source: NOAA Storm Events Database, event_id 1272020. Narrative written by the NWS forecast office that issued the report.