Fog in St Louis, MO

daily fog outlook & 2016–2026 climatology
No fog signal in NWS guidance for the next 48 hours. dense fog (visibility under a mile) is rare here in August.forecast cycle 2026-08-16T00:00:00Z · page rebuilt daily · live layers below update hourly

Measured at St. Louis Lambert International Airport (KSTL). This station is in forecast verification — percentages publish when it clears the accuracy bar.

Measuring stations

stationairportfog hours/yrforecast
KSTLSt. Louis Lambert International Airport21 h/yrverifying
KSUSSpirit of St Louis Airport35 h/yrverifying

Fog is measured where instruments live — airports. Hours/yr = time below CAT I approach minima (visibility under ~½ mile or ceiling under 200 ft), the aviation definition of seriously dense fog.

When St Louis fogs in

Fog here concentrates in January and December — about 21 hours in a typical year at KSTL, usually lasting ~2 h once it forms. Hour-by-hour patterns, live conditions and the forecast strip live on the KSTL station page.

Fog season

January: ~7 hJanFebruary: ~2 hFebMarch: ~1 hMarApril: ~0 hAprMay: ~1 hMayJune: ~0 hJunJuly: ~1 hJulAugust: ~0 hAugSeptember: ~0 hSepOctober: ~0 hOctNovember: ~1 hNovDecember: ~6 hDec
Fog season runs December through February, peaking in January; fog is mostly a 2 AM–9 AM phenomenon; typically thinning out by 1 PM; a typical event lasts about 2 hours once it forms local time · 10-yr average

Machine access: data.json · llms.txt · forecast verification. Not for operational use.