San Juan Islands and Northern Inland Waters Marine Forecast
| Rest Of Tonight...W Wind 20 To 25 Kt With Gusts Up To 30 Kt, Becoming Sw 10 To 15 Kt. Waves Around 3 Ft Early This Evening, Then Around 2 Ft Or Less. A Chance Of Rain Early This Evening. A Slight Chance Of Rain, Then A Chance Of Rain Late. |
| Fri...Sw Wind 10 To 15 Kt. Waves Around 2 Ft Or Less. Rain Likely. |
| Fri Night...S Wind 10 To 15 Kt. Waves Around 2 Ft Or Less. Rain. |
| Sat...S Wind 10 To 15 Kt. Waves Around 2 Ft Or Less. Rain. |
| Sat Night...S Wind 10 To 15 Kt. Waves Around 2 Ft Or Less. Rain. |
| Sun...S Wind 10 To 15 Kt. Waves Around 2 Ft Or Less. Rain. |
| Sun Night...S Wind 10 To 15 Kt. Waves Around 2 Ft Or Less. Rain. |
| Mon...Se Wind 15 To 20 Kt. Waves Around 2 Ft Or Less. Rain. |
| Mon Night...S Wind 15 To 20 Kt. Waves Around 2 Ft Or Less. Rain. |
| Tue...Se Wind 10 To 15 Kt, Easing To 5 To 10 Kt In The Afternoon. Waves Around 2 Ft Or Less. A Chance Of Rain. |
| Tue Night...E Wind 5 To 10 Kt. Waves Around 2 Ft Or Less. A Chance Of Rain. |
| Area Forecast Discussion National Weather Service Seattle WA 828pm PST Thu Dec 18 2025 Snow has fully transitioned to rain at both Snoqualmie and White Pass, with rain being inferred at Stevens Pass based on the temperature observation there. Thus, the winter weather advisory was allowed to expire. There will be a brief period of rain through late tonight before snow levels plummet back to the 1500 to 2000 ft early tomorrow morning. From then on through Saturday, heavy accumulating snow will return to the mountains. Additionally, strong winds continue to blow through the Strait of Juan de Fuca. Strong winds persist right along the coast of the Strait and into Island County. Elsewhere, winds remain elevated but below advisory threshold. Winds should continue to slowly ease tonight. Otherwise the forecast remains on track. See below for updates to marine and aviation. 62 Synopsis A series of weather systems will move across western Washington over the next week, keeping the unsettled conditions ongoing across the area. These unsettled conditions could see periods of lowland rain, mountain snow, and breezy conditions at times throughout the weekend and into the early half of next week. Short Term - Tonight Through Saturday Night Recent radar imagery shows a bulk of rainfall over the southern portions of our area, with most of the heaviest precipitation falling over Oregon. An unsettled and rainy day is still expected over western Washington, with rainfall totals generally around 0.25-0.50 over the lowlands, with locally higher amounts in the South Sound. Snow will continue in the mountains, with snow levels rising this afternoon and evening to 6000 to 7000 feet. As warmer air moves aloft, continuing to monitor the potential for a brief period of freezing rain at the passes, as snow changes to rain. Uncertainty continues on the timing and the depth of the warm layer over the mountains, and how long that lasts for. Snow levels begin to quickly plummet late tonight through Friday downwards to 1500 to 2500 feet, allowing for accumulations to pile up within the Cascades. Therefore, a Winter Storm Warning has been issued for moderate to heavy snowfall at times, as areas like Paradise and Baker could see 2-3 feet, along with Snoqualmie and Stevens seeing a foot to two feet of snow throughout the weekend. Southerly winds will remain elevated this afternoon, around 25 to 35 mph, with occasional gusts 45 to 50 mph possible at times throughout the interior through this evening. Winds will ease by tonight. A surge of westerly winds through the Strait will keep areas like Whidbey Island breezy overnight. The aforementioned system will continue to shift southward on Friday, but conditions still remain unsettled over the area, with lowland rain, mountain snow, and locally breezy conditions at times. Snow levels will stay around 1500-2500 feet, allowing for snowfall to continue in the mountains. Long Term - Sunday Through Thursday Ensembles are in generally good agreement in upper level troughing over the Pacific Northwest through the first half of next week. Additional systems look to move over the area, keeping unsettled conditions over most of the area, with these systems generally remaining on the weaker side. Snow levels look to remain below pass level, which would bring more rounds of mountain snow, with rain expected in the lowlands. Mazurkiewicz Marine A frontal system will is currently traversing northwest Washington. Winds have switched to westerly through the Strait of Juan de Fuca, continuing to produce gale force winds. Elsewhere, winds have backed off to Small Craft Advisory thresholds. Winds should continue to ease overnight into early tomorrow morning, where headlines for the interior waters begin to drop off. Winds and seas remain elevated across the coastal waters, at least through Saturday at this point. The overall pattern remains active across the weekend and into early next week, as additional systems are expected to move across area waters. Seas at 13-16 ft this afternoon will gradually decrease into the weekend to around 10 ft. Additional systems early in the week will lead to elevated seas across the coastal waters. 29/62 Hydrology A weather system continues to move east of the Cascades this afternoon. 12 hour Quantitative Precipitation Forecast amounts in the mountains range 0.50-1.0" with up to 2" in the Cascades of Lewis County and the Olympics. Additional precipitation will continue at times Friday into Saturday, particularly over the Cascades. However, snow levels will fall to near 1500 to 2000 feet on Friday, resulting in snowfall for the mountains above this level. Ongoing river flooding continues for select rivers off the Cascades from King County southwards. For rivers downstream of dams, dam operations to maintain a safe flood pool for area dams could maintain elevated flow levels or they could raise or lower levels downstream of the dams. Dam regulation change rapidly. Additional rises on rivers are expected Friday into Saturday, especially for rivers in Lewis County, due to the ongoing precipitation. For that reason, the Flood Watch has been updated to include Lewis County into the weekend. The Flood Watch remains for King, Pierce, Thurston, and Grays Harbor County due to elevated river levels, especially rivers downstream of dam operations. The landslide threat will remain high through at least Friday. JD NOAA Seattle WA Office: Watches - Warnings - Advisories WA...Wind Advisory until 11pm PST this evening for Island County- Lowlands of Western Skagit and Northwestern Snohomish Counties-Lowlands of Western Whatcom County-San Juan County. Winter Storm Warning from 4am Friday to 4pm PST Saturday for Cascades of Pierce and Lewis Counties-Cascades of Snohomish and Northern King Counties-Cascades of Southern King County-Cascades of Whatcom and Skagit Counties. Flood Watch through Saturday morning for Cascades of Pierce and Lewis Counties-Cascades of Snohomish and Northern King Counties-Cascades of Southern King County-City of Seattle-Eastside-Foothills and Valleys of Central King County-Foothills and Valleys of Pierce and Southern King Counties-Foothills and Valleys of Snohomish and Northern King Counties-Foothills and Valleys of Thurston and Lewis Counties-Foothills of the Western and Southern Olympic Peninsula-Grays Harbor County Coast-Lower Chehalis River Valley-Lowlands of Lewis and Southern Thurston Counties- Lowlands of Pierce and Southern King Counties-Middle Chehalis River Valley-Olympia and Southern Puget Sound- Olympics-Shoreline / Lynnwood / South Everett Area- Willapa and Black Hills. PZ...Small Craft Advisory until 4pm PST Friday for Grays Harbor Bar Gale Warning until 4am PST Friday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca- West Entrance USA Waters Strait Of Juan De Fuca. Small Craft Advisory until 4am PST Friday for Admiralty Inlet Northern Inland Waters Including The San Juan Islands- Puget Sound and Hood Canal Small Craft Advisory until 10pm PST Friday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From Cape Flattery To James Island Out 10 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm- Coastal Waters From James Island To Point Grenville Out 10 Nm- Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm- Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm. |
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