Seattle weather and climate guide

7-day forecast for Seattle

Thursday in Seattle, WA brings mostly cloudy, with a high near 61°F and a low around 52°F. Across the 7-day outlook, highs average 56°F and lows average 48°F, ranging from 43°F to 61°F. 4 of the 7 days carry at least a 30% chance of precipitation, so keep rain gear handy.

Current conditions

Observed at Boeing Field - King County International Airport (KBFI) at 3:53 AM PST.

The rain myth, corrected

Seattle gets less annual precipitation than most of the eastern United States. The difference is intensity. Gulf Coast and East Coast rain arrives in thunderstorms that dump an inch in an hour and move on. Seattle rain arrives as drizzle and light rain from Pacific frontal systems, often a tenth of an inch spread across six hours.

That is why locals genuinely do not carry umbrellas. Light rain and a hooded jacket are compatible in a way that a Florida thunderstorm and a jacket are not. It is also why the city feels wetter than the numbers suggest: you experience rain on far more days, just less of it each time.

Thunderstorms are rare. Seattle averages fewer than ten thunderstorm days a year, compared with over 70 in central Florida. The atmosphere here is stable and cool; the energy for deep convection is usually absent.

The darkness is the real adjustment

At 47.6° north, Seattle is farther north than Quebec City and roughly the latitude of Paris. In late December the sun rises after 7:50 a.m. and sets before 4:20 p.m., giving under eight and a half hours of daylight. Add the persistent low overcast of the wet season and December averages only a couple of hours of actual sunshine per day.

This affects people more than the rain does. Seasonal affective disorder is meaningfully more prevalent at high latitudes with heavy winter cloud, and light therapy lamps are ordinary household objects here. Newcomers from sunnier climates typically find their difficult month is January or February, not the rainiest month of November.

The compensation is June and July, when sunset comes after 9 p.m. and useful twilight lasts past 10. Summer days here are longer than anywhere else in the contiguous United States outside of northern Maine and Minnesota.

Summer is nearly rainless

From roughly early July through mid-September, the Pacific high pressure ridge parks offshore and diverts storm systems north into British Columbia. July averages under an inch of rain. Multi-week rainless stretches are normal, and the record dry streak exceeds 50 days.

The result is a genuinely excellent summer: highs in the upper 70s, low humidity, cool nights, and long evenings. It is also a dry-season climate in the technical sense, which is why the region has a real wildfire season despite its wet reputation. August and September smoke from fires in the Cascades, eastern Washington and British Columbia now degrades Seattle air quality most years, sometimes into unhealthy ranges for days at a time.

The other consequence is that few older homes have air conditioning. That was reasonable for a century and is becoming less so. The late June 2021 heat dome pushed Seattle to 108 °F, an all-time record by five degrees, and killed hundreds of people across the Pacific Northwest. A city without air conditioning is dangerous at 108 in a way that Phoenix is not.

Atmospheric rivers and the wet season

From November through February, the Pacific delivers atmospheric rivers — long, narrow plumes of concentrated water vapor that can transport moisture from near Hawaii to the Washington coast. The informal name is the Pineapple Express.

These events produce the region's serious flooding. Warm, wet air rides up the Olympics and Cascades, wrings out enormous rainfall totals, and melts existing mountain snowpack at the same time — a rain-on-snow event that sends rivers like the Snoqualmie, Skagit and Puyallup over their banks. Landslides on Seattle's steep glacial-till hillsides are a related hazard, and they close rail lines along Puget Sound nearly every winter.

Wind is the other wet-season threat. Deep low pressure systems moving up the coast can bring 50 to 70 mph gusts to Puget Sound, and the region's tall Douglas firs plus overhead power lines make multi-day outages routine. The Hanukkah Eve storm of December 2006 left more than a million customers without power.

Snow, and the convergence zone

Seattle averages about five inches of snow, but the average is nearly meaningless. Many winters produce a dusting; occasional winters produce paralysis. The city sits close enough to sea level and to marine air that most winter storms arrive as rain, and the ones that arrive as snow are usually within a few degrees of changing over.

Steep hills make even modest snow disproportionately disruptive. Two inches on Queen Anne or Capitol Hill effectively closes those neighborhoods to normal traffic.

One local phenomenon deserves explanation: the Puget Sound Convergence Zone. Westerly flow splits around the Olympic Mountains, then rejoins east of the range over the Sound. Where those two streams collide, air is forced upward, generating a narrow band of intense precipitation that can sit over Everett or north Seattle for hours. It can be sunny downtown and snowing hard fifteen miles north. When you see forecast language about convergence-zone snow, that is what it means, and it is why Seattle forecasts frequently contain sharp north-to-south differences.

Weather hazards to know about

• Atmospheric river flooding

  November through February

  Heavy sustained rain, often on melting snowpack, floods Cascade rivers and triggers landslides on steep glacial hillsides.

• Windstorms

  October through March

  Pacific lows bring 50 to 70 mph gusts. Tall conifers plus overhead lines make extended power outages common.

• Wildfire smoke

  August and September

  A newer but now regular hazard. Smoke from regional and Canadian fires can push air quality into unhealthy ranges for days.

• Extreme heat without air conditioning

  Late June through August

  Rare but dangerous, because the housing stock is not built for it. The 2021 heat dome reached 108 °F and caused hundreds of regional deaths.

• Snow and ice on steep terrain

  December through February

  Small accumulations shut down hilly neighborhoods. Convergence-zone bands can make totals vary enormously across short distances.

What to wear and pack, by season

Spring (March to May)

A waterproof shell and layers. Still cool and damp through April; genuinely nice by late May.

Summer (July to mid-September)

Warm-weather clothing plus one warm layer for evenings and any time on the water. Rain gear is largely unnecessary.

Fall (late September to November)

Waterproof jacket, waterproof shoes. This is the wettest stretch of the year.

Winter (December to February)

A warm waterproof layer rather than a heavy parka. Rarely severely cold, reliably wet and dark.