The Chico 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. 11, 1930, the hottest reading for this week of the year since 1906. Next is 85° in 1932.
Chico’s center stands about 210 ft above sea level. Within three miles the land runs from 160 ft to 280 ft, a difference of 120 ft: gently rolling country. The highest named summit within 15 miles is Nimshew Ridge, about 2,770 ft, 15 miles northeast.
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 3 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 14 mi of the line.
Andesite. Age: Late Oligocene to Pleistocene, 2 to 24 million years old. About 8 mi of the line.
Sandstone, conglomerate. Age: Miocene to Pleistocene, less than 23 million years old. About 2 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 Chico reaches San Francisco Bay and the Pacific Ocean by way of Mud Creek and the Sacramento: about 190 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Chico; river miles along the main stem, rounded.
Chico has a hot-summer Mediterranean climate. Summer afternoons average 95° in July; winter nights fall to about 36° in January. About 27 inches of rain fall in a normal year.
On November 14 Chico normally reaches 65° and falls to 40°. The record high is 80°, in 2025; the record low 26°, in 1994. The most rain on this date, 1.37 in, fell in 1953.
Normals 1991–2020 and records since 1906 at Chico University Farm, 3 miles south-southeast. NOAA, through RCC-ACIS.
