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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1° on Nov. 17, 1959, the coldest reading for this week of the year since 1887. Next is 3° in 1933.
St. Charles’s center stands about 760 ft above sea level. Within three miles the land runs from 670 ft to 830 ft, a difference of 160 ft: gently rolling country.
Under the town center the state geologic map shows Silurian System undivided (dolostone, limestone), from the Silurian, 422 to 445 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 60×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Dolostone, limestone. Age: Silurian, 422 to 445 million years old. About 21 mi of the line.
Shale, limestone. Age: Late Ordovician, 445 to 454 million 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 Fox River, the Illinois and the Mississippi: about 1,490 river miles.
Lake on the way: Peoria Lake.
1,190 miles of the trip are on the Mississippi.
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 hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 16° in January. A normal year brings about 28 inches of snow; with the rain, that comes to about 40 inches of water.
On November 14 St. Charles normally reaches 48° and falls to 32°. The record high is 74°, in 1971; the record low 9°, in 1916. The most rain on this date, 1.65 in, fell in 1926.
Normals 1991–2020 and records since 1887 at Aurora Water, 10 miles south. NOAA, through RCC-ACIS.
