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.
Sunny
Mostly sunny; warmer
Mostly sunny
Partly cloudy
Partly cloudy
Partly cloudy
Showers likely
71° on Nov. 16, 1953, the hottest reading for this week of the year since 1886. Next is 71° in 1999.
St. Charles’s center stands about 1,140 ft above sea level. Within three miles the land runs from 1,100 ft to 1,330 ft, a difference of 230 ft: rolling country. The highest named summit within 15 miles is Chance Hollow Hill, about 1,320 ft, 13 miles west-southwest.
Under the town center the state geologic map shows Lower Ordovician (dolostone, sandstone), from the Early Ordovician, 471 to 487 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 33×. 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, sandstone. Age: Early Ordovician, 471 to 487 million years old. About 15 mi of the line.
Shale, limestone, sandstone. Age: Middle Ordovician to Late Ordovician, 445 to 471 million years old. About 6 mi of the line.
Limestone, dolostone. Age: Late Ordovician, 445 to 459 million years old. About 2 mi of the line.
Sandstone, siltstone, shale. Age: Cambrian, 487 to 497 million years old. About 1.0 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 South Fork Whitewater, the Whitewater and the Mississippi: about 1,760 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 warm-summer humid continental climate. Summer afternoons average 80° in July; winter nights fall to about 7° in January. A normal year brings about 53 inches of snow; with the rain, that comes to about 35 inches of water.
On November 14 St. Charles normally reaches 42° and falls to 26°. The record high is 69°, in 2025; the record low −5°, in 1916. The most rain on this date, 0.88 in, fell in 1973.
Normals 1991–2020 and records since 1886 from the Rochester Area threaded record (Rochester International Airport, 22 miles west-southwest, 170 ft higher). NOAA, through RCC-ACIS.
