CYSP — Marathon Airport

fog forecast & climatology · Marathon city page · full 10-year analysis →
No fog signal in NWS guidance for the next 48 hours. September typically brings about 14 hours of dense fog here.forecast cycle 2026-09-04T13:00:00Z · page rebuilt daily · live layers below update hourly

Fog hours per year
329 h below CAT I minima (2016–2026 average)
Fog season
July and May
Typical fog event
~2 h once it forms (middle half 1–4 h, n=456)
Data through
2026-08-15 · machine-readable data.json

When this airport fogs in

In a typical year Marathon Airport spends 329 hours below CAT I approach minima (visibility under ~½ mile or ceiling under 200 ft), concentrated in July and May. The strip above shows the hour-by-hour pattern for the current month from ten years of weather observations.

Fog season

January: ~5 hJanFebruary: ~7 hFebMarch: ~4 hMarApril: ~9 hAprMay: ~19 hMayJune: ~18 hJunJuly: ~27 hJulAugust: ~15 hAugSeptember: ~14 hSepOctober: ~4 hOctNovember: ~6 hNovDecember: ~5 hDec
Fog season is February, April, May, June, July, August, September, peaking in July; fog is mostly a 8 AM–11 AM phenomenon; typically thinning out by 6 PM; 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.