California · Rock climbing · Saratoga

Clamshell Boulder

Clamshell Boulder in California has 5 bouldering routes across 5 difficulty grades.

Photo: fekaylius, CC BY-SA 2.0 (via Flickr)

5 routes

V3 – V10

Bouldering

Best time to visit Clamshell Boulder

Best months: April–November. Best months have typical highs of 55–85 °F, lows of 30 °F or warmer (32 °F where the station doesn't record snow), at most one snowy day and no more than 12 wet days.

Jan
55° / 41°
14 wet
Feb
55° / 40°
14 wet
Mar
58° / 41°
13 wet
Apr
62° / 43°
10 wet
May
67° / 47°
7 wet
Jun
75° / 52°
3 wet
Jul
81° / 58°
1 wet
Aug
81° / 59°
1 wet
Sep
79° / 57°
2 wet
Oct
71° / 52°
6 wet
Nov
60° / 44°
11 wet
Dec
54° / 40°
15 wet

Typical high / low (°F) and days with rain or snow, 1991–2020. Measured at Skyline Ridge Preserve, CA, 7.6 mi away at 2,270 ft. The station sits about 800 ft lower than this place, so expect it a little cooler here. This station doesn't record snowfall. Source: NOAA NCEI U.S. Climate Normals 1991–2020.

Clamshell Boulder is a bouldering area in Sanborn County Park, on county land in California. It sits among several other climbing spots in the park, including Sanborn County Park (Indian Rock Side), Indian Cracks and Hash Rock, all about 0.1 mile away. The area is managed by the county. The climbing here is all bouldering, with five routes ranging from V3 to V10. Static Pinch is the easiest at V3, and Static Reach Sit is the hardest at V10. Clam Digger, a V9, was first climbed by Jeremy Meigs around 1999. Summer is the driest and warmest time to visit. Typical averages from a nearby weather station show July and August highs around 81°F with only about one wet day a month, while winter brings highs in the mid-50s and rain on roughly 14 days a month. That station sits about 780 feet lower than the boulders, so temperatures on the rock run cooler. For a walk, Castle Rock Trail is 0.2 mile away and Skyline Trail is 0.7 mile away. Paddlers can find the San Lorenzo River about 9 miles off.