Fog in Portland, ME
daily fog outlook & 2016–2026 climatology
No fog signal in NWS guidance for the next 48 hours. August typically brings about 5 hours of dense fog here.forecast cycle 2026-08-16T00:00:00Z · page rebuilt daily · live layers below update hourly
Measured at Portland International Jetport (KPWM). This station is in forecast verification — percentages publish when it clears the accuracy bar.
Measuring station
| station | airport | fog hours/yr | forecast |
|---|---|---|---|
| KPWM | Portland International Jetport | 82 h/yr | verifying |
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 Portland fogs in
Fog here concentrates in March and September — about 82 hours in a typical year at KPWM, usually lasting ~2 h once it forms. Hour-by-hour patterns, live conditions and the forecast strip live on the KPWM station page.
Fog season
Fog season is year-round, peaking in March; fog is mostly a 1 AM–8 AM phenomenon; typically thinning out by noon; 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.