The Janesville 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
Mostly sunny
Chance of showers
75° on Nov. 11, 2022, the hottest reading for this week of the year since 1987. Next is 71° in 1989.
Janesville’s center stands about 860 ft above sea level. Within three miles the land runs from 760 ft to 990 ft, a difference of 230 ft: rolling country. The highest named summit within 15 miles is Mount Zion, about 1,080 ft, 5 miles east-northeast.
Under the town center the state geologic map shows Cambrian, undivided (sandstone), from the Cambrian, 487 to 542 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 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. Age: Ordovician, 445 to 487 million years old. About 12 mi of the line.
Sandstone. Age: Ordovician, 445 to 487 million years old. About 9 mi of the line.
Dolostone. Age: Early Ordovician, 471 to 487 million years old. About 2 mi of the line.
Sandstone. Age: Cambrian, 487 to 542 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 Janesville reaches the Gulf of America by way of the Rock River and the Mississippi: about 1,640 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Janesville; river miles along the main stem, rounded.
Janesville has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 12° in January. A normal year brings about 37 inches of snow; with the rain, that comes to about 37 inches of water.
On November 14 Janesville normally reaches 47° and falls to 29°. The record high is 70°, in 1999; the record low 10°, in 1996. The most rain on this date, 0.65 in, fell in 2001.
Normals 1991–2020 and records since 1987 at Afton - Janesville Wwtp, 4 miles southwest. NOAA, through RCC-ACIS.
