The San Ramon plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.
Partly cloudy
Showers likely
Showers likely
Showers likely
Showers likely
Showers likely
Partly cloudy
23° on Nov. 17, 1961, the coldest reading for this week of the year since 1903. Next is 25° in 1978.
San Ramon’s center stands about 650 ft above sea level. Within three miles the land runs from 360 ft to 970 ft, a difference of 610 ft: hilly country. The highest named summit within 15 miles is Mount Diablo, about 3,810 ft, 8 miles north.
Under the town center the state geologic map shows Plio-Pleistocene and Pliocene loosely consolidated deposits (sandstone, conglomerate), from the Miocene to Pleistocene, less than 23 million years old.
The section below crosses 10 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 7×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone, conglomerate. Age: Miocene to Pleistocene, less than 23 million years old. About 6 mi of the line.
Siltstone-mudstone. Age: Early Cretaceous to Late Cretaceous, 66 to 145 million years old. About 6 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 4 mi of the line.
Sandstone, mudstone. Age: Jurassic to Cretaceous, 66 to 202 million years old. About 2 mi of the line.
Coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 2 mi of the line.
Greenstone. Age: Jurassic to Cretaceous, 66 to 202 million years old. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 4 smaller units along the line are not listed.
Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.
A raindrop that lands in San Ramon reaches San Francisco Bay and the Pacific Ocean by way of South San Ramon Creek, the Arroyo de la Laguna, Alameda Creek and Coyote Hills Slough: about 30 river miles.
Often dry. About 60% of the way is mapped as streams that run only after rain or snowmelt; the water makes the whole trip in floods.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of San Ramon; river miles along the main stem, rounded.
San Ramon has a hot-summer Mediterranean climate. Summer afternoons average 89° in July; winter nights fall to about 39° in January. About 15 inches of rain fall in a normal year.
On November 14 San Ramon normally reaches 65° and falls to 43°. The record high is 85°, in 1906; the record low 26°, in 1938. The most rain on this date, 1.02 in, fell in 1953.
Normals 1991–2020 and records since 1903 at Livermore, 11 miles east-southeast, 120 ft lower. NOAA, through RCC-ACIS.
