The Rock Valley 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
Mostly sunny
Mostly cloudy
Partly cloudy
Partly cloudy; cooler
Showers likely
75° on Nov. 13, 1999, the hottest reading for this week of the year since 1899. Next is 74° in 2001.
Rock Valley’s center stands about 1,260 ft above sea level. Within three miles the land runs from 1,220 ft to 1,430 ft, a difference of 210 ft: rolling country.
Under the town center the state geologic map shows Fort Benton Group (shale), from the Late Cretaceous, 90 to 100 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 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.
Shale. Age: Late Cretaceous, 90 to 100 million years old. About 16 mi of the line.
Sandstone, shale. Age: Early Cretaceous to Late Cretaceous, 94 to 113 million years old. About 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.
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 Rock Valley reaches the Gulf of America by way of the Rock River, the Big Sioux, the Missouri and the Mississippi: about 1,990 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 Rock Valley; river miles along the main stem, rounded.
Rock Valley has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 9° in January. A normal year brings about 35 inches of snow; with the rain, that comes to about 30 inches of water.
On November 14 Rock Valley normally reaches 46° and falls to 26°. The record high is 71°, in 2025; the record low −20°, in 1959. The most rain on this date, 1.35 in, fell in 1926.
Normals 1991–2020 and records since 1899 at Sioux Center 2 SE, 12 miles southeast, 100 ft higher. NOAA, through RCC-ACIS.
