The Penn Valley 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
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Showers likely; cooler
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79° on Nov. 13, 1990, the hottest reading for this week of the year since 1966. Next is 79° in 2008.
Penn Valley’s center stands about 1,440 ft above sea level. Within three miles the land runs from 1,190 ft to 1,940 ft, a difference of 750 ft: hilly country. The highest named summit within 15 miles is Banner Mountain, about 3,910 ft, 13 miles east-northeast.
The section below crosses 5 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.
Mafic-volcanic. Age: Jurassic, 145 to 202 million years old. About 13 mi of the line.
Andesite. Age: Late Oligocene to Pleistocene, 2 to 24 million years old. About 5 mi of the line.
Granodiorite. Age: Permian to Tertiary, 2.6 to 260 million years old. About 4 mi of the line.
Diorite, gabbro. Age: Triassic to Cretaceous, 66 to 252 million years old. About 2 mi of the line.
Peridotite, serpentinite. Age: Neoproterozoic to Early Jurassic, 175 to 1,000 million years old. About 0.6 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.
A raindrop that lands in Penn Valley reaches San Francisco Bay and the Pacific Ocean by way of Squirrel Creek, Deer Creek, the Yuba, the Feather and the Sacramento: about 140 river miles.
75 miles of the trip are on the Sacramento.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Penn Valley; river miles along the main stem, rounded.
Penn Valley has a hot-summer Mediterranean climate. Summer afternoons average 88° in July; winter nights fall to about 32° in December. A normal year brings about 9 inches of snow; with the rain, that comes to about 53 inches of water.
On November 14 Penn Valley normally reaches 60° and falls to 37°. The record high is 78°, in 1974; the record low 25°, in 1985. The most rain on this date, 2.86 in, fell in 1981.
Normals 1991–2020 and records since 1966 at Grass Valley No. 2, 7 miles east, 960 ft higher. NOAA, through RCC-ACIS.
