The Keystone 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
Partly cloudy; warmer
Mostly sunny
Partly cloudy
Mostly sunny
Partly cloudy
Showers likely
83° on Nov. 16, 1941, the hottest reading for this week of the year since 1938. Next is 80° in 1999.
Keystone’s center stands about 3,100 ft above sea level. Within three miles the land runs from 3,080 ft to 3,390 ft, a difference of 310 ft: rolling country. The highest named summit within 15 miles is Big Bald Hill, about 3,480 ft, 11 miles east-northeast.
Under the town center the state geologic map shows White River Group (clay), from the Early Oligocene to Late Oligocene, 23 to 34 million years old.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 39×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Siltstone-mudstone, conglomerate-sandstone. Age: Miocene, 5.3 to 23 million years old. About 20 mi of the line.
Clay. Age: Early Oligocene to Late Oligocene, 23 to 34 million years old. About 4 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 Keystone reaches the Gulf of America by way of the North Platte, the Platte, the Missouri and the Mississippi: about 2,130 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 Keystone; river miles along the main stem, rounded.
Keystone has a dry-winter hot-summer continental climate. Summer afternoons average 87° in July; winter nights fall to about 18° in January. A normal year brings about 21 inches of snow; with the rain, that comes to about 19 inches of water.
On November 14 Keystone normally reaches 49° and falls to 29°. The record high is 79°, in 2025; the record low −6°, in 1940. The most rain on this date, 0.40 in, fell in 1993.
Normals 1991–2020 and records since 1938 at Kingsley Dam, 5 miles west, 220 ft higher. NOAA, through RCC-ACIS.
