The Harrison 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.
Partly cloudy
Mostly sunny; warmer
Partly cloudy
Sunny
Mostly sunny
Mostly sunny
Mostly sunny
17° on Nov. 15, 1996, the coldest reading for this week of the year since 1946. Next is 18° in 1967.
Harrison’s center stands about 230 ft above sea level. Within three miles the land runs from 60 ft to 460 ft, a difference of 400 ft: rolling country. The highest named summit within 15 miles is Nonames Hill, about 810 ft, 12 miles north.
Under the town center the state geologic map shows Hartland Formation (amphibolite, pelitic-schist), from the Cambrian to Early Ordovician, 471 to 542 million years old.
The section below crosses 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 27×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Gneiss. Age: Precambrian to Mesoproterozoic. About 7 mi of the line.
Amphibolite, pelitic-schist. Age: Cambrian to Early Ordovician, 471 to 542 million years old. About 5 mi of the line.
Pelitic-schist, gneiss, amphibolite. Age: Early Cambrian to Middle Ordovician, 459 to 542 million years old. About 3 mi of the line.
Unconsolidated. Age: Quaternary, less than 2.6 million years old. About 1 mi of the line.
Hornblende-gneiss. Age: Cambrian to Early Ordovician, 471 to 542 million years old. About 1 mi of the line.
Gneiss. Age: Mesoproterozoic, 1 to 1.6 billion years old. About 0.6 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 2 smaller units 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 Harrison reaches Long Island Sound and the Atlantic Ocean by way of the Mamaroneck: about 7 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Harrison; river miles along the main stem, rounded.
Harrison has a hot-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 23° in January. About 48 inches of rain fall in a normal year.
On November 14 Harrison normally reaches 53° and falls to 37°. The record high is 71°, in 1993; the record low 20°, in 1986. The most rain on this date, 1.92 in, fell in 1972.
Normals 1991–2020 and records since 1946 at Westchester Co Airport, 3 miles north-northeast, 140 ft higher. NOAA, through RCC-ACIS.
