The Mount Hermon 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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89° on Nov. 15, 2008, the hottest reading for this week of the year since 1937. Next is 89° in 2019.
Mount Hermon’s center stands about 520 ft above sea level. Within three miles the land runs from 260 ft to 1,670 ft, a difference of 1,410 ft: steep hill country. The highest named summit within 15 miles is Loma Prieta, about 3,780 ft, 12 miles east-northeast.
Under the town center the state geologic map shows Miocene marine rocks (sandstone, mudstone), from the Oligocene to Pliocene, 2.6 to 34 million years old.
The section below crosses 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 6×. 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, mudstone. Age: Oligocene to Pliocene, 2.6 to 34 million years old. About 7 mi of the line.
Sandstone, mudstone. Age: Jurassic to Cretaceous, 66 to 202 million years old. About 3 mi of the line.
Granodiorite, quartz-monzonite. Age: Early Cretaceous to Late Cretaceous, 66 to 145 million years old. About 2 mi of the line.
Sandstone, mudstone. Age: Miocene to Pleistocene, less than 23 million years old. About 2 mi of the line.
Mudstone, sandstone. Age: Paleocene to Oligocene, 23 to 66 million years old. About 1 mi of the line.
Sandstone, mudstone. Age: Paleocene, 56 to 66 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. 2 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 Mount Hermon reaches the Pacific Ocean by way of Bean Creek, Zayante Creek and the San Lorenzo: about 8 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Mount Hermon; river miles along the main stem, rounded.
Mount Hermon has a warm-summer Mediterranean climate. Summer afternoons average 90° in August; winter nights fall to about 37° in January. About 50 inches of rain fall in a normal year.
On November 14 Mount Hermon normally reaches 72° and falls to 40°. The record high is 88°, in 2021; the record low 27°, in 1985. The most rain on this date, 3.42 in, fell in 1972.
Normals 1991–2020 and records since 1937 at Ben Lomond No. 4, 3 miles north-northwest. NOAA, through RCC-ACIS.
