The Chappaqua 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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17° on Nov. 15, 1996, the coldest reading for this week of the year since 1946. Next is 18° in 1967.
Chappaqua’s center stands about 490 ft above sea level. Within three miles the land runs from 260 ft to 720 ft, a difference of 460 ft: hilly country. The highest named summit within 15 miles is Bald Mountain, about 1,110 ft, 15 miles northwest.
Under the town center the state geologic map shows Fordham Gneiss, undivided, from the Precambrian to Mesoproterozoic.
The section below crosses 11 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.
Gneiss. Age: Precambrian to Mesoproterozoic. About 5 mi of the line.
Gneiss. Age: Precambrian to Mesoproterozoic. About 4 mi of the line.
Gneiss. Age: Middle Ordovician, 459 to 471 million years old. About 4 mi of the line.
Pelitic-schist, gneiss, amphibolite. Age: Early Cambrian to Middle Ordovician, 459 to 542 million years old. About 2 mi of the line.
Schist, gneiss. Age: Early Ordovician to Middle Ordovician, 459 to 487 million years old. About 2 mi of the line.
Unconsolidated. Age: Quaternary, less than 2.6 million years old. About 1 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 5 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 Chappaqua reaches New York Harbor and the Atlantic Ocean by way of the Hudson: about 35 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Chappaqua; river miles along the main stem, rounded.
Chappaqua 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 Chappaqua 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, 7 miles south-southeast, 120 ft lower. NOAA, through RCC-ACIS.
