The Harrisburg 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
79° on Nov. 13, 1999, the hottest reading for this week of the year since 1893. Next is 75° in 1953.
Harrisburg’s center stands about 1,430 ft above sea level. Within three miles the land runs from 1,360 ft to 1,470 ft, a difference of 110 ft: gently rolling country.
Under the town center the state geologic map shows Carlile Shale, from the Late Cretaceous, 66 to 100 million years old.
The section below crosses 4 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, 66 to 100 million years old. About 10 mi of the line.
Quartzite. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 7 mi of the line.
Chert, shale, chalk. Age: Early Cretaceous to Late Cretaceous, 66 to 145 million years old. About 4 mi of the line.
Chalk, marlstone, shale. Age: Late Cretaceous, 66 to 100 million years old. About 3 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 Harrisburg reaches the Gulf of America by way of Ninemile Creek, the Big Sioux, the Missouri and the Mississippi: about 2,030 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 Harrisburg; river miles along the main stem, rounded.
Harrisburg has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 8° in January. A normal year brings about 45 inches of snow; with the rain, that comes to about 28 inches of water.
On November 14 Harrisburg normally reaches 46° and falls to 25°. The record high is 73°, in 2025; the record low −17°, in 1959. The most rain on this date, 1.33 in, fell in 1926.
Normals 1991–2020 and records since 1893 from the Sioux Falls Area threaded record (Sioux Falls Foss Field, 10 miles north-northwest). NOAA, through RCC-ACIS.
