KBOS — Boston Logan International Airport
fog forecast & climatology · Boston city page · full 10-year analysis →
No fog signal in NWS guidance for the next 48 hours. September typically brings about 5 hours of dense fog here.forecast cycle 2026-09-04T13:00:00Z · page rebuilt daily · live layers below update hourly
- Fog hours per year
- 52 h below CAT I minima (2016–2026 average)
- Fog season
- October and September
- Typical fog event
- ~2 h once it forms (middle half 1–3 h, n=190)
- Data through
- 2026-08-15 · machine-readable data.json
When this airport fogs in
In a typical year Boston Logan International Airport spends 52 hours below CAT I approach minima (visibility under ~½ mile or ceiling under 200 ft), concentrated in October and September. The strip above shows the hour-by-hour pattern for the current month from ten years of weather observations.
Fog season
Fog season runs December through October, peaking in October; fog is mostly a 1 AM–9 AM phenomenon; a typical event lasts about 2 hours once it forms local time · 10-yr average
Runway infrastructure
| end | approach lights | best approach | length | RVR |
|---|---|---|---|---|
| 04L | — | LPV | 7,864 ft | RVR |
| 22R | — | — | 7,864 ft | RVR |
| 04R | ALSF-2 | CAT III | 10,006 ft | RVR |
| 22L | MALSF | CAT I | 10,006 ft | RVR |
| 09 | — | — | 7,001 ft | RVR |
| 27 | — | CAT I | 7,001 ft | RVR |
| 14 | — | — | 5,000 ft | — |
| 32 | — | — | 5,000 ft | — |
| 15L | — | — | 2,557 ft | — |
| 33R | — | — | 2,557 ft | — |
| 15R | MALSR | CAT I | 10,083 ft | RVR |
| 33L | ALSF-2 | CAT III | 10,083 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.