The Pompeys Pillar 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
Partly cloudy
Partly cloudy
Chance of showers
Chance of showers
Mostly cloudy
Chance of showers
81° on Nov. 13, 1999, the hottest reading for this week of the year since 1911. Next is 75° in 1990.
Pompeys Pillar’s center stands about 2,890 ft above sea level. Within three miles the land runs from 2,840 ft to 3,290 ft, a difference of 450 ft: hilly country. The highest named summit within 15 miles is Lookout Point, about 3,610 ft, 15 miles north-northwest.
Under the town center the state geologic map shows Gravel, from the Pleistocene to Holocene, less than 1.8 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 18×. 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. Age: Late Cretaceous, 66 to 84 million years old. About 8 mi of the line.
Shale. Age: Late Cretaceous, 72 to 84 million years old. About 6 mi of the line.
Sandstone. Age: Early Paleocene, 62 to 66 million years old. About 5 mi of the line.
Shale, sandstone, bentonite. Age: Early Paleocene, 62 to 66 million years old. About 3 mi of the line.
Gravel, sand, silt. Age: Pleistocene to Holocene, less than 1.8 million years old. About 1 mi of the line.
Age: Pleistocene to Holocene, less than 1.8 million years old. About 0.9 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 Pompeys Pillar reaches the Gulf of America by way of the Yellowstone, the Missouri and the Mississippi: about 3,070 river miles.
Lakes on the way: Lake Oahe, Lake Sakakawea, Lake Sharpe and Lake Francis Case.
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 Pompeys Pillar; river miles along the main stem, rounded.
Pompeys Pillar has a cold semi-arid climate. Summer afternoons average 87° in July; winter nights fall to about 12° in January. A normal year brings about 34 inches of snow; with the rain, that comes to about 14 inches of water.
On November 14 Pompeys Pillar normally reaches 47° and falls to 21°. The record high is 72°, in 2025; the record low −26°, in 1959. The most rain on this date, 0.45 in, fell in 1941.
Normals 1991–2020 and records since 1911 at Huntley Experimental Station, 15 miles west-southwest, 140 ft higher. NOAA, through RCC-ACIS.
