The Gem 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.
Chance of showers
Partly cloudy
Mostly sunny
Partly cloudy
Mostly sunny
Partly cloudy
Chance of showers; warmer
82° on Nov. 15, 2025, the hottest reading for this week of the year since 1950. Next is 81° in 1999.
Gem’s center stands about 3,090 ft above sea level. Within three miles the land runs from 3,000 ft to 3,120 ft, a difference of 120 ft: gently rolling country.
Under the town center the state geologic map shows Loess (silt), from the Pleistocene to Holocene, less than 2.6 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 60×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Silt. Age: Pleistocene to Holocene, less than 2.6 million years old. About 22 mi of the line.
Arkose. Age: Miocene, 5.3 to 23 million years old. About 2 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 Gem reaches the Gulf of America by way of the North Fork Solomon, the Solomon, the Smoky Hill, the Kansas, the Missouri and the Mississippi: about 2,170 river miles.
Lakes on the way: Waconda Lake and Kirwin Reservoir.
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 Gem; river miles along the main stem, rounded.
Gem has a hot-summer humid continental climate. Summer afternoons average 91° in July; winter nights fall to about 15° in January. A normal year brings about 27 inches of snow; with the rain, that comes to about 20 inches of water.
On November 14 Gem normally reaches 55° and falls to 25°. The record high is 81°, in 1999; the record low −2°, in 1959. The most rain on this date, 0.23 in, fell in 1993.
Normals 1991–2020 and records since 1950 at Colby 1 SW, 9 miles west-southwest. NOAA, through RCC-ACIS.
