The Jefferson 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.
Partly cloudy
Mostly sunny; warmer
Mostly sunny
Partly cloudy
Partly cloudy
Mostly sunny
Showers likely
78° on Nov. 13, 1999, the hottest reading for this week of the year since 1889. Next is 77° in 1971.
Jefferson’s center stands about 1,120 ft above sea level. Within three miles the land runs from 1,090 ft to 1,120 ft, a difference of 30 ft: nearly flat ground. The highest named summit within 15 miles is Indian Hill, about 1,410 ft, 14 miles west-northwest.
Under the town center the state geologic map shows Dakota Formation (sandstone), from the Early Cretaceous to Late Cretaceous, 66 to 145 million years old.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 47×. 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 9 mi of the line.
Sandstone. Age: Early Cretaceous to Late Cretaceous, 66 to 145 million years old. About 8 mi of the line.
Shale, limestone. Age: Late Cretaceous, 66 to 100 million years old. About 3 mi of the line.
Shale. Age: Late Cretaceous, 66 to 100 million years old. About 2 mi of the line.
Sandstone, shale. Age: Early Cretaceous to Late Cretaceous, 94 to 113 million years old. About 1 mi of the line.
Sandstone, shale. Age: Early Cretaceous, 100 to 145 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.
A raindrop that lands in Jefferson reaches the Gulf of America by way of the Big Sioux, the Missouri and the Mississippi: about 1,910 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 Jefferson; river miles along the main stem, rounded.
Jefferson has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 10° in January. A normal year brings about 36 inches of snow; with the rain, that comes to about 29 inches of water.
On November 14 Jefferson normally reaches 48° and falls to 26°. The record high is 76°, in 2025; the record low −9°, in 1959. The most rain on this date, 1.08 in, fell in 1926.
Normals 1991–2020 and records since 1889 from the Sioux City Area threaded record (Sioux City Airport, 17 miles south-southeast). NOAA, through RCC-ACIS.
