The Hysham 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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79° on Nov. 12, 1999, the hottest reading for this week of the year since 1945. Next is 76° in 1990.
Hysham’s center stands about 2,660 ft above sea level. Within three miles the land runs from 2,610 ft to 2,840 ft, a difference of 230 ft: rolling country. The highest named summit within 15 miles is Rattlesnake Butte, about 3,160 ft, 8 miles east-southeast.
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 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 19×. 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. Age: Late Cretaceous, 72 to 84 million years old. About 9 mi of the line.
Age: Pleistocene to Holocene, less than 1.8 million years old. About 7 mi of the line.
Sandstone. Age: Late Cretaceous, 66 to 84 million years old. About 3 mi of the line.
Sandstone. 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 2 mi of the line.
Shale, sandstone, bentonite. Age: Early Paleocene, 62 to 66 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.
A raindrop that lands in Hysham reaches the Gulf of America by way of the Yellowstone, the Missouri and the Mississippi: about 3,010 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 Hysham; river miles along the main stem, rounded.
Hysham has a cold semi-arid climate. Summer afternoons average 88° in July; winter nights fall to about 12° in January. A normal year brings about 37 inches of snow; with the rain, that comes to about 15 inches of water.
On November 14 Hysham normally reaches 47° and falls to 24°. The record high is 72°, in 2025; the record low −21°, in 1959. The most rain on this date, 0.28 in, fell in 1996.
Normals 1991–2020 and records since 1945 at Hysham, here. NOAA, through RCC-ACIS.
