The Humboldt 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.
79° on Nov. 13, 1999, the hottest reading for this week of the year since 1893. Next is 75° in 1953.
Humboldt’s center stands about 1,700 ft above sea level. Within three miles the land runs from 1,550 ft to 1,720 ft, a difference of 170 ft: gently rolling country.
Under the town center the state geologic map shows Cretaceous, undifferentiated (chert, shale, chalk), from the Early Cretaceous to Late Cretaceous, 66 to 145 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 53×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Quartzite. Age: Paleoproterozoic, 1.6 to 2.5 billion years old. About 16 mi of the line.
Chert, shale, chalk. Age: Early Cretaceous to Late Cretaceous, 66 to 145 million years old. About 8 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 Humboldt reaches the Gulf of America by way of the East Fork Vermillion, the Vermillion, the Missouri and the Mississippi: about 2,050 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 Humboldt; river miles along the main stem, rounded.
Humboldt 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 Humboldt 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, 17 miles east-southeast, 280 ft lower). NOAA, through RCC-ACIS.