October Fog Log

As we said in the original Fog Log post, we’re keeping track of that crucial “September to November period when fire risk is greatest,” according to the UCSF letter.

“Mount Sutro is squarely in the fog belt. The question is, Whether between the end of summer (and fog) and the beginning of winter (and rain), is there enough dryness to raise fire risk? We’ll find out. What we’re starting here is a Fog Log. It will be updated for every day’s weather. We will also look out for the “dry hot winds” blowing “from the Northeast.” There is a link from the front page.

September had only 7 days that were fogless (i.e. no fog morning or evening). And, these were interspersed with fog-days; the maximum consecutive number of fogless days was 2.

October had 13 fogless days; the longest stretch without fog (or rain) was 7 days. It also had 4 rainy days.


This is the October Fog Log, week by week.

October 1st week: Four fogless days, cool and bright. Started with sunny bright days on Oct 1, 2, 3, 4, no fog. Chill north-westerly winds on 3rd and 4th. Oct 4th, the weather report says 83% humidity.

October 2nd week: Two sunny days, for a fogless streak of seven days. Cloudy/ foggy rest of the week. No dry hot winds. Oct 5, sunny and cool. Humidity about 74%. No dry hot winds yet. Oct 6, bright and sunny. Oct 7 started out sunny, but around 2 p.m. the fog’s back. That ends a one-week fogless streak (Sept 30-Oct). Oct 8 – cloudy. Oct 9th high clouds and sun. Oct 10 Overcast. Oct 11 Overcast.

Night fog over Forest Knolls (view fm Twin Peaks)

Night fog over Forest Knolls (view fm Twin Peaks)

October 3rd week: Rainy 3; “fogless” 1; Foggy, 3. October 12, cloudy with humidity at 80%; evening rain. Oct 13: rainstorm overnight, most of the day. Oct 14: Cloudy. Oct 15: Rain. Oct 16 and 17: Morning mist, then sunny, then evening fog. Oct 18: Foggy.

October 4th week: Rainy 1; Fogless 2; Foggy, 4. Oct 19: Rain. Oct 20: Sunny, then fog. Oct 21: Sunny. State of the forest: damp. Some trails on the east side were already dry after yesterday’s rain, but by the side of the trail, the duff was wet under a layer of fallen leaves. The Native Garden had some grass sprouting, not sure if it’s native or not. And the fog returned at night. Oct 22: Morning fog, the sunny. Oct 23: Sunny. Oct 24: Morning fog, clearing to sunshine. Oct 25: Sunny.

The duff was wet above the dried-out trail

The duff was wet above the dried-out trail

October Final Week: Sunny, 4: Foggy, 2 (6 days) Oct 26: Sunny, evening fog. Oct 27, 28, 29, 30: Sunny. Oct 31: Very foggy.

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