Berryessa Peak, on Napa and Yolo County lines, California

Elevation = 3062 ft. (933 meters)
Looking north at the long trail to Berryessa Peak where it runs under the ridge top for 1.6 miles. There is a very good report on hiking this peak at the Yolohiker website. Through a lot of work over many years a public easement has been established through some areas of private land. Below are pictures and map of the route I did on June 6, 2014. It was warm that day and I suggest waiting until cooler weather with temperatures below 70. Peakbagger.com page.
Gail Hanna crossing the fence at the top of a steep section on the trail. This is at point 199 shown on the topo map below. Note the post with BPT marking the route.
The above map has a UTM grid using NAD 27. I have a GPS file available for the above route. Berryessa.gpx The starting point is at waypoint 193 which is very close to Milepost 20.0 on the Knoxville Road. A small sign indicates no motorized vehicles are allowed, but it doesn't say it is the trail to Berryessa Peak. The route follows an old road which turns into a trail at about point 198 where is goes steeply up a hill. At 199 is the stile crossing a fence. The trail runs under the ridge top and drops into a canyon at point 204 at 1890 feet elevation. From there you have a gain of 800 feet up to the ridge top then a slight drop of about 80 feet to the road at point 213. Then another 1.25 miles to the top on a good road with a gain of 450 feet. I measure the route to be 15 miles round-trip with a gain of about 2900 feet on the ascent. There is a gain of about 300 feet on the return. This is a hard hike if it is warm so take plenty of water, at least four quarts. In my case the ascent took 5 hours and then 3 1/2 hours to return. 6/14 RLC
The summit used to have a fire lookout which was built on this foundation in 1948. The building was destroyed in the 39,000 acre Rumsey Fire in October 2004.
This is looking north from the upper ridge at about waypoint 211. You can see parts of the trail running along under the ridge top. It's a long way back to the trailhead from here. If it's warm you will be thinking about your water supply!
Reference Mark #2 named Monticello is south of the lookout. The peak was first surveyed in 1880. Datasheet.