The Ottawa 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.
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2° on Nov. 12, 2019, the coldest reading for this week of the year since 1995. Next is 4° in 2014.
Ottawa’s center stands about 960 ft above sea level. Within three miles the land runs from 850 ft to 1,110 ft, a difference of 260 ft: rolling country. The highest named summit within 15 miles is Lapham Hill, about 1,250 ft, 5 miles northeast.
Under the town center the state geologic map shows Maquoketa Formation (shale, dolostone), 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 57×. 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.
Dolostone. Age: Silurian, 422 to 445 million years old. About 7 mi of the line.
Shale, dolostone. Age: Ordovician, 445 to 487 million years old. About 6 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 Ottawa reaches the Gulf of America by way of the Bark, the Rock River and the Mississippi: about 1,700 river miles.
Lake on the way: Lake Koshkonong.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Ottawa; river miles along the main stem, rounded.
Ottawa has a warm-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 11° in January. A normal year brings about 51 inches of snow; with the rain, that comes to about 38 inches of water.
On November 14 Ottawa normally reaches 46° and falls to 28°. The record high is 69°, in 1999; the record low 10°, in 1996. The most rain on this date, 0.45 in, fell in 2001.
Normals 1991–2020 and records since 1995 at Sullivan 3 SE - Wfo Mkx, 5 miles west. NOAA, through RCC-ACIS.
