The Angostura 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.
Mostly cloudy
Sunny; warmer
Mostly sunny
Partly cloudy
Mostly sunny; cooler
Partly cloudy
Showers likely
−21° on Nov. 14, 1959, the coldest reading for this week of the year since 1894. Next is −16° in 2014.
Angostura’s center stands about 3,400 ft above sea level. Within three miles the land runs from 3,170 ft to 3,440 ft, a difference of 270 ft: rolling country. The highest named summit within 15 miles is Horse Trap Mountain, about 4,680 ft, 14 miles west-northwest.
Under the town center the state geologic map shows Eolian Deposits (silt, sand), from the Quaternary, less than 2.6 million years old.
The section below crosses 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 15×. 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, fine-detrital. Age: Quaternary, less than 2.6 million years old. About 7 mi of the line.
Silt, sand. Age: Quaternary, less than 2.6 million years old. About 6 mi of the line.
Claystone, conglomerate, sandstone. Age: Early Cretaceous, 100 to 145 million years old. About 5 mi of the line.
Shale, siltstone, sandstone. Age: Permian to Early Triassic, 247 to 260 million years old. About 2 mi of the line.
Siltstone, sandstone, shale. Age: Permian, 252 to 299 million years old. About 2 mi of the line.
Sandstone, siltstone, claystone. Age: Middle Jurassic to Late Jurassic, 145 to 175 million years old. About 0.7 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 3 smaller units 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 Angostura reaches the Gulf of America by way of the Cheyenne, the Missouri and the Mississippi: about 2,530 river miles.
Lakes on the way: Lake Oahe, Lake Sharpe, Lake Francis Case and Lewis and Clark Lake.
1,170 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Angostura; river miles along the main stem, rounded.
Angostura has a hot-summer humid continental climate. Summer afternoons average 89° in July; winter nights fall to about 14° in January. A normal year brings about 32 inches of snow; with the rain, that comes to about 19 inches of water.
On November 14 Angostura normally reaches 51° and falls to 23°. The record high is 76°, in 1934; the record low −21°, in 1959. The most rain on this date, 0.40 in, fell in 1927.
Normals 1991–2020 and records since 1894 at Hot Springs, 10 miles north-northwest, 160 ft higher. NOAA, through RCC-ACIS.
