The Mason City 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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3° on Nov. 17, 1959, the coldest reading for this week of the year since 1906. Next is 4° in 2019.
Mason City’s center stands about 580 ft above sea level. Within three miles the land runs from 510 ft to 610 ft, a difference of 100 ft: gently rolling country.
Under the town center the state geologic map shows Carbondale Formation (shale, sandstone, coal), from the Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old.
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, sandstone, coal. Age: Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old. About 24 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 Mason City reaches the Gulf of America by way of Salt Creek, the Sangamon, the Illinois and the Mississippi: about 1,330 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Mason City; river miles along the main stem, rounded.
Mason City has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 18° in January. A normal year brings about 19 inches of snow; with the rain, that comes to about 40 inches of water.
On November 14 Mason City normally reaches 52° and falls to 32°. The record high is 77°, in 1999; the record low 8°, in 1940. The most rain on this date, 1.20 in, fell in 1926.
Normals 1991–2020 and records since 1906 at Lincoln, 19 miles east. NOAA, through RCC-ACIS.
