What the app shows you
Full FogCast score, fog type, chase-or-skip verdict, and 10-day outlook — all in the app.
Get LightCast Suite on iOS
Know before you drive: FogCast checks the conditions that produce photogenic fog
Get more than a snapshot of current conditions. The LightCast app unlocks everything to plan ahead
Humidity alone isn't enough. Wind alone isn't enough. Cloud cover alone isn't enough. Photogenic valley fog requires several conditions to line up at once, and most weather apps don't read them together.
Set a FogCast threshold once. The app will alert you when conditions at your saved locations look promising, so you're not manually checking at 4am.
Don't waste a sunrise drive. Check FogCast before you leave.
Download on the App StoreMuir Woods National Monument sits in a coastal redwood canyon on the flanks of Mount Tamalpais, less than a kilometer from the Pacific marine layer's primary inland pathway. The old-growth redwoods here reach 80 meters and the canyon floor stays cool and humid year-round, making it a reliable location for atmospheric forest fog regardless of season.
When marine layer rolls in from the coast it flows down into the canyon and pools around the redwood trunks, creating layered light shafts as the fog diffuses the morning sun. The main trail along Redwood Creek offers the most direct compositions. The Cathedral Grove section is particularly photogenic, with the fog hanging at mid-canopy height and the light filtering through in columns.
Fog is most reliable in summer, matching the Bay Area marine layer pattern, but the canyon's sheltered position means mist lingers longer than on open hillsides. Early morning visits before the park fills with day visitors produce the most atmospheric conditions.