The Sylvester 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
Mostly sunny
Partly cloudy
Partly cloudy
Chance of showers
70° on Nov. 11, 2022, the hottest reading for this week of the year since 1940. Next is 68° in 2025.
Sylvester’s center stands about 930 ft above sea level. Within three miles the land runs from 810 ft to 1,070 ft, a difference of 260 ft: rolling country. The highest named summit within 15 miles is Liberty Pole Hill, about 1,110 ft, 15 miles north-northeast.
Under the town center the state geologic map shows Ancell Group (sandstone), from the Ordovician, 445 to 487 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 58×. 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. Age: Ordovician, 445 to 487 million years old. About 11 mi of the line.
Sandstone. Age: Ordovician, 445 to 487 million years old. About 11 mi of the line.
Dolostone. Age: Early Ordovician, 471 to 487 million years old. About 3 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 Sylvester reaches the Gulf of America by way of Sylvester Creek, the Sugar, the Pecatonica, the Rock River and the Mississippi: about 1,660 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Sylvester; river miles along the main stem, rounded.
Sylvester has a hot-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 11° in January. A normal year brings about 42 inches of snow; with the rain, that comes to about 40 inches of water.
Normals 1991–2020 and records since 1940 at Monroe Wwtp, 7 miles west-southwest. NOAA, through RCC-ACIS.
