CYYT — St. John's International Airport
fog forecast & climatology · St. John's city page · full 10-year analysis →
Forecast feed initializing for this station. September typically brings about 33 hours of dense fog here (10-year average).
- Fog hours per year
- 535 h below CAT I minima (2016–2026 average)
- Fog season
- May and April
- Typical fog event
- ~2 h once it forms (middle half 1–4 h, n=1541)
- Data through
- 2026-08-15 · machine-readable data.json
When this airport fogs in
In a typical year St. John's International Airport spends 535 hours below CAT I approach minima (visibility under ~½ mile or ceiling under 200 ft), concentrated in May and April. The strip above shows the hour-by-hour pattern for the current month from ten years of weather observations.
Fog season
Fog season runs September through July, peaking in May; fog here can hit at any hour of the day; a typical event lasts about 2 hours once it forms local time · 10-yr average
Runway infrastructure
| end | approach lights | best approach | length | RVR |
|---|---|---|---|---|
| 10 | ALSF-2 | CAT III | 8,502 ft | RVR |
| 28 | ALSF-2 | CAT III | 8,502 ft | RVR |
| 16 | SSALR | CAT I | 7,005 ft | RVR |
| 34 | — | LPV | 7,005 ft | RVR |
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.