The Walnut Grove 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.
Sunny
Mostly sunny; warmer
Sunny
Partly cloudy
Mostly sunny
Mostly sunny
Mostly sunny
12° on Nov. 15, 1969, the coldest reading for this week of the year since 1955. Next is 13° in 2019.
Walnut Grove’s center stands about 900 ft above sea level. Within three miles the land runs from 690 ft to 940 ft, a difference of 250 ft: rolling country.
Under the town center the state geologic map shows St. Louis Limestone and Warsaw Limestone, from the Carboniferous, 324 to 359 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 39×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Limestone. Age: Carboniferous, 324 to 359 million years old. About 15 mi of the line.
Shale, limestone. Age: Ordovician, 445 to 487 million years old. About 7 mi of the line.
Chert. Age: Carboniferous, 324 to 359 million years old. About 2 mi of the line.
Limestone. Age: Carboniferous, 324 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 Walnut Grove reaches the Gulf of America by way of Roney Creek, the South Fork Red, the Red River, the Cumberland, the Ohio and the Mississippi: about 1,240 river miles.
Lake on the way: Bards Lake.
970 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Walnut Grove; river miles along the main stem, rounded.
Walnut Grove has a humid subtropical climate. Summer afternoons average 89° in July; winter nights fall to about 27° in January. About 54 inches of rain fall in a normal year, with about 2 inches of snow.
On November 14 Walnut Grove normally reaches 59° and falls to 38°. The record high is 77°, in 1964; the record low 15°, in 2019. The most rain on this date, 1.54 in, fell in 2024.
Normals 1991–2020 and records since 1955 at Portland Sewage Plant, 9 miles northeast, 110 ft lower. NOAA, through RCC-ACIS.
