Fog in Riverside, CA

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 March Air Reserve Base (KRIV). This station is in forecast verification — percentages publish when it clears the accuracy bar.

Measuring stations

stationairportfog hours/yrforecast
KRIVMarch Air Reserve Base48 h/yrverifying
KRALRiverside Municipal Airport21 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 Riverside fogs in

Fog here concentrates in December and January — about 48 hours in a typical year at KRIV, usually lasting ~2 h once it forms. Hour-by-hour patterns, live conditions and the forecast strip live on the KRIV station page.

Fog season

January: ~11 hJanFebruary: ~5 hFebMarch: ~3 hMarApril: ~3 hAprMay: ~3 hMayJune: ~2 hJunJuly: ~0 hJulAugust: ~0 hAugSeptember: ~1 hSepOctober: ~5 hOctNovember: ~5 hNovDecember: ~11 hDec
Fog season runs October through May, peaking in January; fog is mostly a 4 AM–7 AM phenomenon; typically thinning out by 9 AM; 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.