The Algonquin 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.
Mostly sunny
Sunny; warmer
Mostly sunny
Mostly sunny
Partly cloudy
Partly cloudy
Partly cloudy
75° on Nov. 11, 2022, the hottest reading for this week of the year since 1983. Next is 74° in 1999.
Algonquin’s center stands about 750 ft above sea level. Within three miles the land runs from 720 ft to 930 ft, a difference of 210 ft: rolling country.
Under the town center the state geologic map shows Maquoketa Formation or Group (shale, limestone), from the Late Ordovician, 445 to 454 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 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.
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 Algonquin reaches the Gulf of America by way of the Fox River, the Illinois and the Mississippi: about 1,520 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 Algonquin; river miles along the main stem, rounded.
Algonquin has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 14° in January. A normal year brings about 32 inches of snow; with the rain, that comes to about 40 inches of water.
On November 14 Algonquin normally reaches 48° and falls to 31°. The record high is 74°, in 1999; the record low 4°, in 1986. The most rain on this date, 0.48 in, fell in 2024.
Normals 1991–2020 and records since 1983 at Elgin Water, 7 miles south. NOAA, through RCC-ACIS.
