Mount Saint Helena is the highest point in the San Francisco Bay Area watershed, and its East Peak is the high point of Napa County. It is located on the boundaries between Napa, Sonoma, and Lake counties, about 80-90 miles north of San Francisco. It is of volcanic origin, situated in the general area of Clear Lake Volcanic Field, a geologically active area with numerous geysers and hot springs. From the summit on a clear day Lassen Peak, High Sierra, Snow Mountain, Mount Diablo, Mount Tamalpais, Pacific Ocean are all visible. With a binocular you can even see the high-rise buildings in downtown San Francisco.
Mount Saint Helena has a summit plateau bordered by five sub-peaks. North Peak is the highest point. The edges of the summit plateau drops off precipitously to the surrounding valleys. A fire road (gated) goes to the top, where there are radio and TV antennas. Most of the hike is along the fire road, however the lowest 1 mile is a hiking trail if you use the hiker's trailhead. Along the fire road there are numerous rock outcrops popular for technical rock climbing.
clayperez's (edited) comments about biking up Mt. St. Helena: it is a rewarding 5 mile up-hill journey to the 4343 foot summit. You start right around 2200 feet at the fire road entrance. There is a gate but you can easily hoist your bike over it after parking just down the road a little bit. Be extremely cautious of traffic when crossing the highway to the entrance. Many drivers think they're competing in the Indy 500 when they drive this stretch of highway so WATCH OUT.
Once you reach the top keep an eye out for some of the outstanding features of California. All of this is hard to take in at one time especially if the weather isn't on your side. Try to go on a clear day or just after a storm. If you can swing it, go early before the sun rises and you'll be rewarded with a SPECTACULAR sunrise. I always bring a camera. Every day presents something new. So Mount Saint Helena is one of those places that should be visited over and over agian. It's gaining popularity though and it is often almost impossible to find a place to park. So go early!
Take Highway 29 north from Calistoga, where it becomes a winding highway climbing up the hills. You will see the sign "Robert Louis Stevenson State Park", named after the famous writer who tried to mine silver here in the 1860's. A few miles past the sign the road reaches a saddle before descending to Lake County. The hiker's trailhead (2300 feet) is on the left side of the road at the saddle, parking area is on the right. Further north for ~500 feet is the biker's trailhead (2200 feet) which leads directly onto the (gated) fire road, also on the west side of the road. The distance to North Peak of Mount St. Helena is about 5.5 miles from either trailhead.
Follow the hiking trail for 1 mile until you come out onto the fire road. Remember the location of the turn off, since the trail sign is somewhat hidden. Go left (up) on the fire road. After reaching the summit plateau there are turn offs that lead to South Peak, Middle Peak, etc. Follow the main road to North Peak.
Any season. Avoid rainy days to prevent trail erosion. Summer afternoons can be hot on the fire road, because of lack of shades. However, the summit plateau is always breezy.
USGS - 7.5 min Mt. St. Helena and Detert Reservoir
AAA - Sonoma and Napa Counties, Bay and River Area, North Bay Counties
Camping is not permitted in Robert Louis Stevenson State Park. In Bothe-Napa Valley state park there is a developed campground, which is about 20 miles south of Calistoga on Highway 29. Commercial lodging or camping can be found in Calistoga or other nearby towns: Santa Rosa, St. Helena, Napa, Sonoma, Clear Lake.
There are camping facilities at Bothe-Napa Valley State Park approximately 15 miles from the parking lot at Robert Louis Stevenson State Park. There are group camping facilities which can accommodate 30 people ($22), and family camps which accommodate eight people and one car per campsite ($12 per night). Reservation is recommended (you may make reservations up to 7 months prior to your arrival date). Phone: 707-942-4575. Online reservations
Mount Saint Helena was named after a princess of Russia, during the 18th century when Russians established a trading post (Fort Ross) on the Pacific coast about 40 miles west.
Robert Lewis Stevenson was a Scottish novelist and poet famous for Treasure Island and The Strange Case of Dr. Jekyll and Mr. Hyde. He and his wife, during their honeymoon, squatted on the side of Mt St Helena. They made the remains of the old Silverado mine site their home as they explored the area. Stevenson wrote The Silverado Squatters in 1883 documenting his adventures at the ghost mine. We found and entered this mine during our hike, it’s said this place inspired the “treasure grotto” in Treasure Island. This is a very interesting place with a rich history and unique natural wonder; it’s a fine example of California’s lesser known treasures. (credit to Squishy)