The Castlewood 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 sunny
Mostly sunny; warmer
Mostly sunny
Partly cloudy
Partly cloudy
Partly cloudy; cooler
Showers likely
−11° on Nov. 14, 1940, the coldest reading for this week of the year since 1893. Next is −10° in 1959.
Castlewood’s center stands about 1,690 ft above sea level. Within three miles the land runs from 1,670 ft to 1,820 ft, a difference of 150 ft: gently rolling country. The highest named summit within 15 miles is Buffalo Hill, about 2,010 ft, 11 miles northeast.
Under the town center the state geologic map shows Pierre Shale (shale, bentonite), from the Late Cretaceous, 66 to 100 million years old.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 55×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale, bentonite. Age: Late Cretaceous, 66 to 100 million years old. About 24 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.
A raindrop that lands in Castlewood reaches the Gulf of America by way of the Big Sioux, the Missouri and the Mississippi: about 2,220 river miles.
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 Castlewood; river miles along the main stem, rounded.
Castlewood has a warm-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 3° in January. A normal year brings about 41 inches of snow; with the rain, that comes to about 23 inches of water.
On November 14 Castlewood normally reaches 40° and falls to 22°. The record high is 68°, in 2025; the record low −11°, in 1940. The most rain on this date, 0.80 in, fell in 1909.
Normals 1991–2020 and records since 1893 at Watertown Regional Airport, 14 miles north-northwest. NOAA, through RCC-ACIS.
