Fog in Saint John, NB

daily fog outlook & 2016–2026 climatology
Some chance of fog — peaks at 23% around 6 am Sunday.forecast cycle 2026-08-16T00:00:00Z · page rebuilt daily · live layers below update hourly

Measured at Saint John Airport (CYSJ). Forecast percentages for this station have passed live verification.

Measuring station

stationairportfog hours/yrforecast
CYSJSaint John Airport282 h/yrlive forecast

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 Saint John fogs in

Fog here concentrates in July and August — about 282 hours in a typical year at CYSJ, usually lasting ~2 h once it forms. Hour-by-hour patterns, live conditions and the forecast strip live on the CYSJ station page.

Fog season

January: ~2 hJanFebruary: ~12 hFebMarch: ~16 hMarApril: ~10 hAprMay: ~24 hMayJune: ~38 hJunJuly: ~70 hJulAugust: ~51 hAugSeptember: ~32 hSepOctober: ~15 hOctNovember: ~6 hNovDecember: ~2 hDec
Fog season runs May through September, peaking in July; fog is mostly a 11 PM–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.