The Santa Rosa Valley 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. 16, 2020, the hottest reading for this week of the year since 1923. Next is 95° in 2021.
Santa Rosa Valley’s center stands about 450 ft above sea level. Within three miles the land runs from 220 ft to 1,030 ft, a difference of 810 ft: hilly country. The highest named summit within 15 miles is Santa Paula Peak, about 4,880 ft, 15 miles north-northwest.
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 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.
Basalt, andesite. Age: Late Oligocene to Late Miocene, 8 to 25 million years old. About 9 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: Miocene to Pleistocene, less than 23 million years old. About 5 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 2 mi of the line.
Sandstone, conglomerate. Age: Middle Eocene to Early Miocene, 16 to 48 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. 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 Santa Rosa Valley reaches the Pacific Ocean by way of the Arroyo Santa Rosa, Conejo Creek and Calleguas Creek: about 19 river miles.
Often dry. About 100% of the way is mapped as streams that run only after rain or snowmelt; the water makes the whole trip in floods.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Santa Rosa Valley; river miles along the main stem, rounded.
Santa Rosa Valley has a cold semi-arid climate. Summer afternoons average 80° in August; winter nights fall to about 44° in December. About 12 inches of rain fall in a normal year.
On November 14 Santa Rosa Valley normally reaches 73° and falls to 49°. The record high is 94°, in 1949; the record low 34°, in 2000. The most rain on this date, 1.63 in, fell in 1953.
Normals 1991–2020 and records since 1923 from the Camarillo Area threaded record (Camarillo Airport, 11 miles west-southwest, 380 ft lower). NOAA, through RCC-ACIS.
