The Mendon 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
Partly cloudy; warmer
Sunny
Sunny
Partly cloudy
Partly cloudy
Partly cloudy
3° on Nov. 17, 1959, the coldest reading for this week of the year since 1901. Next is 5° in 2019.
Mendon’s center stands about 770 ft above sea level. Within three miles the land runs from 610 ft to 780 ft, a difference of 170 ft: gently rolling country.
Under the town center the state geologic map shows St. Louis Limestone, from the Middle Mississippian, 331 to 347 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 62×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Limestone. Age: Middle Mississippian, 331 to 347 million years old. About 7 mi of the line.
Limestone, shale. Age: Early Mississippian, 347 to 359 million years old. About 6 mi of the line.
Limestone. Age: Middle Mississippian, 331 to 347 million years old. About 6 mi of the line.
Shale, sandstone, coal. Age: Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old. About 4 mi of the line.
Clay, silt, sand. Age: Holocene, less than 12,000 years old. About 0.5 mi of the line.
Shale, sandstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 million years old. About 0.4 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 1 smaller unit along the line are not listed.
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 Mendon reaches the Gulf of America by way of Ursa Creek and the Mississippi: about 1,320 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Mendon; river miles along the main stem, rounded.
Mendon has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 19° in January. About 36 inches of rain fall in a normal year.
On November 14 Mendon normally reaches 52° and falls to 34°. The record high is 76°, in 2025; the record low 9°, in 1940. The most rain on this date, 1.03 in, fell in 1926.
Normals 1991–2020 and records since 1901 from the Quincy Area threaded record (Quincy Regional Airport, 12 miles south-southeast). NOAA, through RCC-ACIS.
