The Los Osos 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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30° on Nov. 16, 1998, the coldest reading for this week of the year since 1893. Next is 31° in 1982.
Los Osos’s center stands about 130 ft above sea level. Within three miles the land runs from 0 ft to 1,180 ft, a difference of 1,180 ft: steep hill country. Open water lies within three miles. The highest named summit within 15 miles is Lopez Mountain, about 2,860 ft, 14 miles east.
Under the town center the state geologic map shows Quaternary sand deposits, unit 1 (coastal), from the Quaternary, less than 2.6 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 8×. 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: Jurassic to Cretaceous, 66 to 202 million years old. About 5 mi of the line.
Sand. Age: Quaternary, less than 2.6 million years old. About 4 mi of the line.
Serpentinite. Age: Middle Jurassic to Late Jurassic, 145 to 175 million years old. About 2 mi of the line.
Siltstone-mudstone. Age: Early Cretaceous, 113 to 145 million years old. About 1 mi of the line.
Greenstone. Age: Jurassic to Cretaceous, 66 to 202 million years old. About 0.9 mi of the line.
Coarse-detrital. Age: Quaternary, less than 2.6 million years old. About 0.9 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit 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 Los Osos reaches the Pacific Ocean by way of Los Osos Creek: about 3 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Los Osos; river miles along the main stem, rounded.
Los Osos has a warm-summer Mediterranean climate. Summer afternoons average 80° in August; winter nights fall to about 44° in January. About 22 inches of rain fall in a normal year.
On November 14 Los Osos normally reaches 71° and falls to 48°. The record high is 88°, in 2021; the record low 33°, in 1929. The most rain on this date, 2.67 in, fell in 1972.
Normals 1991–2020 and records since 1893 at San Luis Obispo Poly, 10 miles east, 180 ft higher. NOAA, through RCC-ACIS.
