The Copperopolis 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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83° on Nov. 11, 2025, the hottest reading for this week of the year since 1992. Next is 82° in 2016.
Copperopolis’s center stands about 680 ft above sea level. Within three miles the land runs from 510 ft to 1,450 ft, a difference of 940 ft: steep hill country. The highest named summit within 15 miles is Bear Mountain, about 2,880 ft, 6 miles north-northeast.
Under the town center the state geologic map shows Mesozoic volcanic rocks, unit 2 (Western Sierra Foothills and Western Klamath Mountains) (mafic-volcanic), from the Jurassic, 145 to 202 million years old.
The section below crosses 9 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 10 mi of the line.
Slate, graywacke. Age: Triassic to Late Jurassic, 145 to 252 million years old. About 5 mi of the line.
Sandstone, conglomerate. Age: Miocene to Pleistocene, less than 23 million years old. About 2 mi of the line.
Mafic-volcanic, greenstone. Age: Paleozoic to Mesozoic, 66 to 542 million years old. About 2 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 1 mi of the line.
Peridotite, serpentinite. Age: Neoproterozoic to Early Jurassic, 175 to 1,000 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. 3 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 Copperopolis reaches San Francisco Bay and the Pacific Ocean by way of the Stanislaus, the San Joaquin and New York Slough: about 140 river miles.
70 miles of the trip are on the San Joaquin.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Copperopolis; river miles along the main stem, rounded.
Copperopolis has a hot-summer Mediterranean climate. Summer afternoons average 97° in July; winter nights fall to about 38° in January. About 30 inches of rain fall in a normal year.
On November 14 Copperopolis normally reaches 66° and falls to 45°. The record high is 81°, in 1999; the record low 37°, in 2022. The most rain on this date, 2.12 in, fell in 2025.
Normals 1991–2020 and records since 1992 at New Melones Dam Headquarters, 9 miles east-northeast, 280 ft higher. NOAA, through RCC-ACIS.
