The Union 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
78° on Nov. 11, 2022, the hottest reading for this week of the year since 1948. Next is 74° in 2020.
Union’s center stands about 850 ft above sea level. Within three miles the land runs from 810 ft to 980 ft, a difference of 170 ft: gently rolling country.
Under the town center the state geologic map shows Galena Group (Trenton Limestone) (dolostone, limestone), from the Late Ordovician, 447 to 459 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.
Shale, limestone. Age: Late Ordovician, 445 to 454 million years old. About 21 mi of the line.
Dolostone, limestone. Age: Late Ordovician, 447 to 459 million years old. About 2 mi of the line.
Dolostone, limestone. Age: Silurian, 422 to 445 million years old. About 2 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 Union reaches the Gulf of America by way of the Kishwaukee, the Rock River and the Mississippi: about 1,620 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Union; river miles along the main stem, rounded.
Union has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 13° in January. A normal year brings about 34 inches of snow; with the rain, that comes to about 37 inches of water.
On November 14 Union normally reaches 49° and falls to 30°. The record high is 70°, in 1999; the record low 10°, in 1996. The most rain on this date, 0.59 in, fell in 2024.
Normals 1991–2020 and records since 1948 at Mchenry Stratton Lock/Dam, 16 miles east-northeast, 110 ft lower. NOAA, through RCC-ACIS.
