The Altona 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
Partly cloudy
Partly cloudy
Partly cloudy; cooler
Showers likely
75° on Nov. 14, 1999, the hottest reading for this week of the year since 1877. Next is 72° in 1949.
Altona’s center stands about 1,670 ft above sea level. Within three miles the land runs from 1,620 ft to 1,750 ft, a difference of 130 ft: gently rolling country. The highest named summit within 15 miles is Stony Point, about 1,970 ft, 13 miles east.
Under the town center the state geologic map shows Sioux Quartzite (quartzite, mudstone), from the Paleoproterozoic, 1.6 to 2 billion years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 44×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Conglomerate, sandstone, mudstone. Age: Late Cretaceous, 72 to 100 million years old. About 11 mi of the line.
Quartzite, mudstone. Age: Paleoproterozoic, 1.6 to 2 billion years old. About 5 mi of the line.
Chert, shale, chalk. Age: Early Cretaceous to Late Cretaceous, 66 to 145 million years old. About 3 mi of the line.
Shale, bentonite. Age: Late Cretaceous, 66 to 100 million years old. About 3 mi of the line.
Quartzite. Age: Paleoproterozoic, 1.6 to 2.5 billion 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 Altona reaches the Gulf of America by way of the Big Sioux, the Missouri and the Mississippi: about 2,140 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 Altona; river miles along the main stem, rounded.
Altona has a warm-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 5° in January. A normal year brings about 40 inches of snow; with the rain, that comes to about 29 inches of water.
On November 14 Altona normally reaches 42° and falls to 23°. The record high is 75°, in 1999; the record low −12°, in 1959. The most rain on this date, 0.38 in, fell in 2024.
Normals 1991–2020 and records since 1877 at Pipestone, 10 miles south-southeast. NOAA, through RCC-ACIS.
