The Port Costa 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.
Partly cloudy
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89° on Nov. 14, 2010, the hottest reading for this week of the year since 1950. Next is 82° in 2025.
Port Costa’s center stands about 150 ft above sea level. Within three miles the land runs from 0 ft to 830 ft, a difference of 830 ft: hilly country. Open water lies within three miles. The highest named summit within 15 miles is Vollmer Peak, about 1,890 ft, 11 miles south.
Under the town center the state geologic map shows Upper Cretaceous marine rocks, unit 1 (Upper Great Valley Sequence) (sandstone, siltstone-mudstone), from the Late Cretaceous, 66 to 100 million years old.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 31×. 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 5 mi of the line.
Sandstone, siltstone-mudstone. Age: Late Cretaceous, 66 to 100 million years old. About 3 mi of the line.
Coarse-detrital. Age: Pleistocene, less than 2.6 million years old. About 3 mi of the line.
Sandstone, mudstone. Age: Oligocene to Pliocene, 2.6 to 34 million years old. About 2 mi of the line.
Sandstone, mudstone. Age: Paleocene, 56 to 66 million years old. About 1 mi of the line.
Volcanic. Age: Middle Miocene to Late Miocene, 8 to 12 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 Port Costa runs straight into San Francisco Bay and the Pacific Ocean.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Port Costa; river miles along the main stem, rounded.
Port Costa has a warm-summer Mediterranean climate. Summer afternoons average 75° in September; winter nights fall to about 44° in January. About 24 inches of rain fall in a normal year.
On November 14 Port Costa normally reaches 65° and falls to 49°. The record high is 89°, in 2010; the record low 34°, in 1985. The most rain on this date, 1.53 in, fell in 1952.
Normals 1991–2020 and records since 1950 at Richmond, 14 miles southwest, 130 ft lower. NOAA, through RCC-ACIS.
