The Dexter 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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−7° on Nov. 13, 2019, the coldest reading for this week of the year since 1949. Next is 5° in 1972.
Dexter’s center stands about 340 ft above sea level. Within three miles the land runs from 240 ft to 450 ft, a difference of 210 ft: rolling country. The highest named summit within 15 miles is Underwood Hill, about 1,160 ft, 13 miles southeast.
Under the town center the state geologic map shows Black River Group (limestone), from the Middle Ordovician, 459 to 471 million years old.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 26×. 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 Ordovician, 459 to 471 million years old. About 14 mi of the line.
Limestone. Age: Middle Ordovician, 459 to 471 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.
Rain that falls on Dexter runs only a short way, about 2 miles, to Lake Ontario. From the lake it goes down the St. Lawrence to the Atlantic.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Dexter; river miles along the main stem, rounded.
Dexter has a warm-summer humid continental climate. Summer afternoons average 79° in July; winter nights fall to about 10° in January. About 37 inches of rain fall in a normal year.
On November 14 Dexter normally reaches 47° and falls to 30°. The record high is 68°, in 1994; the record low 13°, in 1996. The most rain on this date, 0.90 in, fell in 1985.
Normals 1991–2020 and records since 1949 at Watertown International Airport, here. NOAA, through RCC-ACIS.
