The Costa Mesa 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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34° on Nov. 17, 1958, the coldest reading for this week of the year since 1921. Next is 37° in 1938.
Costa Mesa’s center stands about 100 ft above sea level. Within three miles the land runs from 0 ft to 210 ft, a difference of 210 ft: rolling country. Open water lies within three miles. The highest named summit within 15 miles is Signal Peak, about 1,160 ft, 7 miles east-southeast.
Under the town center the state geologic map shows Older Quaternary alluvium and marine deposits (coarse-detrital), from the Pleistocene, less than 2.6 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 18×. 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 9 mi of the line.
Coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 7 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 3 mi of the line.
Sandstone, mudstone. Age: Miocene to Pleistocene, less than 23 million years old. About 0.4 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.
Rain that falls on Costa Mesa runs straight into the Pacific Ocean.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Costa Mesa; river miles along the main stem, rounded.
Costa Mesa has a cold semi-arid climate. Summer afternoons average 74° in September; winter nights fall to about 50° in January. About 9 inches of rain fall in a normal year.
On November 14 Costa Mesa normally reaches 69° and falls to 55°. The record high is 81°, in 1940; the record low 39°, in 1938. The most rain on this date, 1.11 in, fell in 1944.
Normals 1991–2020 and records since 1921 at Newport Beach Harbor, 3 miles southeast. NOAA, through RCC-ACIS.
