I did some searches but didn't see any good compilation of norcal trails and how they handle rain. I'll rank a few of my trails and hopefully others will follow suit. Feel free to disagree.
Ranking: 1-5 stars
1 star= total slop for weeks after a drizzle
3 stars= wont be fun for 2-3 days or so after
5 stars= could ride with confidence after a monsoon
Skeggs: 1 star on BB, SM, and Resolution, maybe 2 for the fire roads
Russian ridge: 3 stars with a few 1 star sections hawk and ancient oaks,
Water dog lake: 2 stars
Montara mtn: 3 stars, fire road 5 stars
Tamarancho: 2- 3 stars
China Camp: 5 stars
Saratoga gap: ?
Annadel: ?
Henry Coe: ?
Ranking: 1-5 stars
1 star= total slop for weeks after a drizzle
3 stars= wont be fun for 2-3 days or so after
5 stars= could ride with confidence after a monsoon
Skeggs: 1 star on BB, SM, and Resolution, maybe 2 for the fire roads
Russian ridge: 3 stars with a few 1 star sections hawk and ancient oaks,
Water dog lake: 2 stars
Montara mtn: 3 stars, fire road 5 stars
Tamarancho: 2- 3 stars
China Camp: 5 stars
Saratoga gap: ?
Annadel: ?
Henry Coe: ?