The Santa Ana 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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26° on Nov. 12, 1938, the coldest reading for this week of the year since 1906. Next is 30° in 1919.
Santa Ana’s center stands about 120 ft above sea level. Within three miles the land runs from 40 ft to 210 ft, a difference of 170 ft: gently rolling country. The highest named summit within 15 miles is Sierra Peak, about 3,030 ft, 14 miles east-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 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 20×. 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 15 mi of the line.
Sandstone, mudstone. Age: Oligocene to Pliocene, 2.6 to 34 million years old. About 5 mi of the line.
Sandstone, conglomerate. Age: Middle Eocene to Early Miocene, 16 to 48 million years old. About 0.7 mi of the line.
Coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 0.6 mi of the line.
Basalt, andesite. Age: Late Oligocene to Late Miocene, 8 to 25 million years old. About 0.5 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 Santa Ana runs straight into the Pacific Ocean.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Santa Ana; river miles along the main stem, rounded.
Santa Ana has a hot semi-arid climate. Summer afternoons average 85° in August; winter nights fall to about 48° in December. About 12 inches of rain fall in a normal year.
On November 14 Santa Ana normally reaches 75° and falls to 53°. The record high is 100°, in 1933; the record low 30°, in 1938. The most rain on this date, 1.83 in, fell in 1946.
Normals 1991–2020 and records since 1906 at Santa Ana Fire Station, here. NOAA, through RCC-ACIS.
