The Oskaloosa 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.
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Partly cloudy; warmer
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78° on Nov. 13, 1999, the hottest reading for this week of the year since 1948. Next is 77° in 2016.
Oskaloosa’s center stands about 850 ft above sea level. Within three miles the land runs from 710 ft to 850 ft, a difference of 140 ft: gently rolling country.
Under the town center the state geologic map shows Lower Cherokee Group and Raccoon Creek Group (shale, sandstone, siltstone), from the Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 million years old.
The section below crosses 3 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, sandstone, siltstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 million years old. About 12 mi of the line.
Dolostone, limestone. Age: Middle Mississippian to Late Mississippian, 324 to 347 million years old. About 12 mi of the line.
Dolostone, limestone. Age: Early Mississippian to Middle Mississippian, 331 to 359 million years old. About 0.5 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 Oskaloosa reaches the Gulf of America by way of Little Muchakinock Creek, Muchakinock Creek, the Des Moines and the Mississippi: about 1,460 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Oskaloosa; river miles along the main stem, rounded.
Oskaloosa has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 14° in January. A normal year brings about 24 inches of snow; with the rain, that comes to about 37 inches of water.
On November 14 Oskaloosa normally reaches 50° and falls to 30°. The record high is 75°, in 2025; the record low 4°, in 1959. The most rain on this date, 0.70 in, fell in 1968.
Normals 1991–2020 and records since 1948 at Ottumwa Industrial Airport, 17 miles southeast. NOAA, through RCC-ACIS.
