LFRN — Rennes-Saint-Jacques Airport

fog forecast & climatology · Saint-Jacques-de-la-Lande, Ille-et-Vilaine city page · full 10-year analysis →
No fog forecast feed exists for this station. September typically brings about 10 hours of dense fog here (10-year average).

Fog hours per year
168 h below CAT I minima (2016–2026 average)
Fog season
October and December
Typical fog event
~2 h once it forms (middle half 1–4 h, n=596)
Data through
2026-08-15 · machine-readable data.json

When this airport fogs in

In a typical year Rennes-Saint-Jacques Airport spends 168 hours below CAT I approach minima (visibility under ~½ mile or ceiling under 200 ft), concentrated in October and December. The strip above shows the hour-by-hour pattern for the current month from ten years of weather observations.

Fog season

January: ~18 hJanFebruary: ~20 hFebMarch: ~11 hMarApril: ~10 hAprMay: ~8 hMayJune: ~3 hJunJuly: ~1 hJulAugust: ~4 hAugSeptember: ~10 hSepOctober: ~30 hOctNovember: ~27 hNovDecember: ~29 hDec
Fog season runs September through May, peaking in October; fog is mostly a 2 AM–10 AM phenomenon; typically thinning out by noon; a typical event lasts about 2 hours once it forms local time · 10-yr average

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.