The San Lorenzo 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.
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85° on Nov. 15, 2008, the hottest reading for this week of the year since 1948. Next is 77° in 2005.
San Lorenzo’s center stands about 40 ft above sea level. Within three miles the land runs from 0 ft to 520 ft, a difference of 520 ft: hilly country. Open water lies within three miles. The highest named summit within 15 miles is Sunol Peak, about 2,160 ft, 12 miles east-southeast.
Under the town center the state geologic map shows Quaternary alluvium and marine deposits (coarse-detrital), from the Pleistocene to Holocene, less than 2.6 million years old.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 10×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 6 mi of the line.
Sandstone, mudstone. Age: Oligocene to Pliocene, 2.6 to 34 million years old. About 4 mi of the line.
Siltstone-mudstone. Age: Early Cretaceous to Late Cretaceous, 66 to 145 million years old. About 3 mi of the line.
Sandstone, conglomerate. Age: Miocene to Pleistocene, less than 23 million years old. About 3 mi of the line.
Serpentinite. Age: Middle Jurassic to Late Jurassic, 145 to 175 million years old. About 0.7 mi of the line.
Coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 0.3 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale.
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.
Rain that falls on San Lorenzo runs straight into San Francisco Bay and the Pacific Ocean.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of San Lorenzo; river miles along the main stem, rounded.
San Lorenzo has a warm-summer Mediterranean climate. Summer afternoons average 74° in September; winter nights fall to about 42° in January. About 19 inches of rain fall in a normal year.
On November 14 San Lorenzo normally reaches 64° and falls to 46°. The record high is 82°, in 2008; the record low 37°, in 2000. The most rain on this date, 0.68 in, fell in 1968.
Normals 1991–2020 and records since 1948 at Oakland International Airport, 6 miles west-northwest. NOAA, through RCC-ACIS.
