Fog in Murphysboro, IL

daily fog outlook & 2016–2026 climatology
No fog signal in NWS guidance for the next 48 hours. August typically brings about 10 hours of dense fog here.forecast cycle 2026-08-16T00:00:00Z · page rebuilt daily · live layers below update hourly

Measured at Southern Illinois Airport (KMDH). This station is in forecast verification — percentages publish when it clears the accuracy bar.

Measuring station

stationairportfog hours/yrforecast
KMDHSouthern Illinois Airport64 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 Murphysboro fogs in

Fog here concentrates in September and August — about 64 hours in a typical year at KMDH, usually lasting ~1 h once it forms. Hour-by-hour patterns, live conditions and the forecast strip live on the KMDH station page.

Fog season

January: ~5 hJanFebruary: ~3 hFebMarch: ~3 hMarApril: ~4 hAprMay: ~1 hMayJune: ~1 hJunJuly: ~4 hJulAugust: ~10 hAugSeptember: ~15 hSepOctober: ~8 hOctNovember: ~6 hNovDecember: ~5 hDec
Fog season is January, April, July, August, September, October, November, December, peaking in September; fog is mostly a 1 AM–6 AM phenomenon; typically thinning out by 8 AM; a typical event lasts about 1 hour once it forms local time · 10-yr average

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