CYSJ — Saint John Airport

fog forecast & climatology · Saint John city page · full 10-year analysis →
Some chance of fog — peaks at 32% around 6 am Saturday.forecast cycle 2026-09-04T13:00:00Z · page rebuilt daily · live layers below update hourly

Fog hours per year
282 h below CAT I minima (2016–2026 average)
Fog season
July and August
Typical fog event
~2 h once it forms (middle half 1–3 h, n=1018)
Data through
2026-08-15 · machine-readable data.json

When this airport fogs in

In a typical year Saint John Airport spends 282 hours below CAT I approach minima (visibility under ~½ mile or ceiling under 200 ft), concentrated in July and August. The strip above shows the hour-by-hour pattern for the current month from ten years of weather observations.

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

Runway infrastructure

endapproach lightsbest approachlengthRVR
05SSALRCAT I7,000 ftRVR
23SSALRCAT I7,000 ftRVR

From FAA NASR / curated AIP Canada research. Approach-light class and minima tier drive how low an approach can be flown — details in the chase board.

For flight operations

EFVS crews: the CHASE board ranks airports by live fog status, approach lighting, go-around height and flight time from your base. Forecast probabilities publish here per-airport once the calibrated model beats climatology on live verification — receipts on the scorecard. Methodology.

Sources: NOAA/NWS National Blend of Models guidance · METAR observations 2016–2026 (Iowa Environmental Mesonet) · FAA NASR. Machine access: data.json · llms.txt. Not for operational use.