Fog in Seattle, WA

daily fog outlook & 2016–2026 climatology
Fog unlikely through Sunday (peak 2%). August typically brings about 2 hours of dense fog here.forecast cycle 2026-08-16T00:00:00Z · page rebuilt daily · live layers below update hourly

Measured at Seattle–Tacoma International Airport (KSEA). Forecast percentages for this station have passed live verification.

Measuring stations

stationairportfog hours/yrforecast
KSEASeattle–Tacoma International Airport85 h/yrlive forecast
KBFIKing County International Airport - Boeing Field37 h/yrverifying

Fog is measured where instruments live — airports. Hours/yr = time below CAT I approach minima (visibility under ~½ mile or ceiling under 200 ft), the aviation definition of seriously dense fog.

When Seattle fogs in

Fog here concentrates in January and December — about 85 hours in a typical year at KSEA, usually lasting ~2 h once it forms. Hour-by-hour patterns, live conditions and the forecast strip live on the KSEA station page.

Fog season

January: ~21 hJanFebruary: ~5 hFebMarch: ~2 hMarApril: ~1 hAprMay: ~3 hMayJune: ~1 hJunJuly: ~1 hJulAugust: ~2 hAugSeptember: ~2 hSepOctober: ~14 hOctNovember: ~15 hNovDecember: ~20 hDec
Fog season runs October through January, peaking in January; fog is mostly a 2 AM–9 AM phenomenon; typically thinning out by 11 AM; a typical event lasts about 2 hours once it forms local time · 10-yr average

Machine access: data.json · llms.txt · forecast verification. Not for operational use.