Lake BerryessaLake Berryessa at a Glance
About Lake Berryessa
Lake Berryessa is a large reservoir in Napa County, California, formed by the impoundment of Putah Creek behind Monticello Dam. It is a prominent regional recreational lake and a local water-supply reservoir.
The reservoir offers boating, fishing, camping and shoreline recreation with multiple access points and marinas. A visually distinctive engineering feature is the dam’s bell-mouth spillway, commonly known as the “Glory Hole,” which functions as the lake’s principal overflow when levels are high.
Monticello Dam was constructed in the mid-20th century and the reservoir was created to store water for regional irrigation and municipal use; the facility also became a recreational resource as access and marinas developed. The dam was completed in 1957.
Lake Berryessa lies in Napa County in northern California, set within a largely rural and hilly landscape and accessed from several local roads and communities that serve the lake’s recreation sites.
- Dam and creation date: Created by the Monticello Dam, which was completed in 1957, the reservoir is a major water body in Napa County used for recreation and water supply.
- Spillway feature: The dam includes a bell-mouth spillway popularly called the “Glory Hole,” which is visible when the reservoir reaches high levels.
What to See#
- Monticello Dam (and spillway): Monticello Dam blocks Putah Creek and creates the reservoir; the dam’s bell-mouth spillway is a noted engineering feature and local landmark.
Best Time to Visit Lake Berryessa
Best visited in late spring through summer for boating and water recreation; winter brings higher inflow and chances to see the spillway in action.
Weather & Climate near Lake Berryessa
Lake Berryessa's climate is classified as Hot-Summer Mediterranean - Hot-Summer Mediterranean climate with warm summers (peaking in July) and cold winters (coldest in January). Temperatures range from 4°C to 33°C. Moderate rainfall (644 mm/year) with a pronounced dry season.
| Month | Comfort | Temp | Feels | Rain | Sky | Humidity | Wind | UV | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | - | 4° - 13° | 7° | 142 mm | - | - | 2.4 m/s | - | - |
| February | - | 5° - 15° | 9° | 116 mm | - | - | 2.7 m/s | - | - |
| March | - | 6° - 18° | 12° | 90 mm | - | - | 3.2 m/s | - | - |
| April | - | 7° - 21° | 14° | 32 mm | - | - | 3.4 m/s | - | - |
| May | - | 10° - 25° | 18° | 12 mm | - | - | 3.6 m/s | - | - |
| June | - | 13° - 30° | 21° | 4 mm | - | - | 3.8 m/s | - | - |
| July | - | 14° - 33° | 24° | 1 mm | - | - | 3.4 m/s | - | - |
| August | - | 14° - 32° | 23° | 2 mm | - | - | 3.1 m/s | - | - |
| September | - | 13° - 30° | 21° | 10 mm | - | - | 2.7 m/s | - | - |
| October | - | 10° - 25° | 17° | 34 mm | - | - | 2.4 m/s | - | - |
| November | - | 6° - 18° | 12° | 95 mm | - | - | 2.3 m/s | - | - |
| December | - | 4° - 13° | 7° | 106 mm | - | - | 2.3 m/s | - | - |
How to Get to Lake Berryessa
Drive: From Napa, take CA-121/29 to Monticello Road and follow signs to the lake (about 45-60 minutes). From Sacramento, travel west on I-80 and US-50 to CA-16 and follow local roads toward the lake. Several public boat ramps and recreation areas are marked off the main access roads.
Tips for Visiting Lake Berryessa
- Stop at the Lake Berryessa Visitors Center (if open) for maps and updated boat ramp information.
- To see the Monticello 'Glory Hole' spillway, aim for winter and spring after heavy rains when levels force water through the bell-mouth.
- Boat fuel and services are limited; plan ahead and check the current water level-recreation areas close when levels drop.