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 sunny
Mostly sunny; warmer
Partly cloudy
Mostly cloudy
Chance of showers
Partly cloudy
Chance of showers
66° on Nov. 15, 1939, the hottest reading for this week of the year since 1893. Next is 66° in 2005.
Keystone’s center stands about 850 ft above sea level. Within three miles the land runs from 830 ft to 860 ft, a difference of 30 ft: nearly flat ground.
Under the town center the state geologic map shows Granodiorite to hornblende diorite, locally magmatically foliated (granodiorite, diorite), from the Neoarchean, 2.5 to 2.8 billion years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Granodiorite, diorite. Age: Neoarchean, 2.5 to 2.8 billion years old. About 12 mi of the line.
Limestone, dolostone. Age: Late Ordovician, 445 to 459 million years old. About 5 mi of the line.
Granite, granodiorite. Age: Neoarchean, 2.5 to 2.8 billion years old. About 3 mi of the line.
Granitic. Age: Neoarchean, 2.5 to 2.8 billion years old. About 3 mi of the line.
Shale, sandstone. Age: Ordovician, 445 to 487 million years old. About 1 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.
Keystone has a warm-summer humid continental climate. Summer afternoons average 80° in July; winter nights fall to about −1° in January. A normal year brings about 49 inches of snow; with the rain, that comes to about 23 inches of water.
On November 14 Keystone normally reaches 36° and falls to 20°. The record high is 62°, in 2025; the record low −17°, in 1919. The most rain on this date, 1.09 in, fell in 1944.
Normals 1991–2020 and records since 1893 at Grand Forks University (Nws), 14 miles west-southwest. NOAA, through RCC-ACIS.
