The Castaic 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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95° on Nov. 13, 2013, the hottest reading for this week of the year since 1939. Next is 94° in 2021.
Castaic’s center stands about 1,230 ft above sea level. Within three miles the land runs from 1,040 ft to 2,220 ft, a difference of 1,180 ft: steep hill country. The highest named summit within 15 miles is Burnt Peak, about 5,780 ft, 14 miles north.
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 7 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.
Sandstone, mudstone. Age: Oligocene to Pliocene, 2.6 to 34 million years old. About 8 mi of the line.
Sandstone, conglomerate. Age: Miocene to Pleistocene, less than 23 million years old. About 5 mi of the line.
Sandstone, mudstone. Age: Miocene to Pleistocene, less than 23 million years old. About 4 mi of the line.
Sandstone, mudstone. Age: Paleocene, 56 to 66 million years old. About 3 mi of the line.
Coarse-detrital. Age: Pleistocene to Holocene, less than 2.6 million years old. About 3 mi of the line.
Orthogneiss. Age: Paleoproterozoic to Miocene, 5.3 to 2,500 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. 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 Castaic reaches the Pacific Ocean by way of Castaic Creek and the Santa Clara: about 45 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Castaic; river miles along the main stem, rounded.
Castaic has a hot semi-arid climate. Summer afternoons average 89° in August; winter nights fall to about 44° in December. About 14 inches of rain fall in a normal year.
On November 14 Castaic normally reaches 73° and falls to 49°. The record high is 93°, in 2021; the record low 35°, in 1985. The most rain on this date, 1.04 in, fell in 1953.
Normals 1991–2020 and records since 1939 from the Burbank Glendale Pasadena Area threaded record (Burbank Glendale Pasadena Airport, 25 miles southeast, 500 ft lower). NOAA, through RCC-ACIS.
