The St. Charles 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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4.30 inches of rain fell in two days, the most for this week of the year since records began in 1930. The next wettest, 4.20 inches, fell in 2015.
St. Charles’s center stands about 210 ft above sea level. Within three miles the land runs from 140 ft to 240 ft, a difference of 100 ft: gently rolling country.
Under the town center the state geologic map shows Terrace deposits (coarse-detrital, fine-detrital), from the Pleistocene, less than 2.6 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.
Coarse-detrital, fine-detrital. Age: Pleistocene, less than 2.6 million years old. About 14 mi of the line.
Coarse-detrital, fine-detrital. Age: Holocene, less than 12,000 years old. About 6 mi of the line.
Coarse-detrital, fine-detrital. Age: Holocene, less than 12,000 years old. About 4 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 St. Charles reaches the Gulf of America by way of the White River and the Mississippi: about 670 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of St. Charles; river miles along the main stem, rounded.
St. Charles has a humid subtropical climate. Summer afternoons average 90° in July; winter nights fall to about 32° in January. About 52 inches of rain fall in a normal year, with about 1 inch of snow.
On November 14 St. Charles normally reaches 63° and falls to 42°. The record high is 86°, in 1955; the record low 24°, in 2018. The most rain on this date, 2.08 in, fell in 1957.
Normals 1991–2020 and records since 1930 at Saint Charles, here. NOAA, through RCC-ACIS.
