The Pelham 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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76° on Nov. 11, 2020, the hottest reading for this week of the year since 1948. Next is 75° in 1993.
Pelham’s center stands about 170 ft above sea level. Within three miles the land runs from 130 ft to 510 ft, a difference of 380 ft: rolling country. The highest named summit within 15 miles is Warner Hill, about 620 ft, 11 miles north-northeast.
Under the town center the state geologic map shows Merrimack Group, Berwick Formation (granofels, biotite-schist), from the Ordovician to Silurian, 422 to 487 million years old.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 37×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Granofels, biotite-schist. Age: Ordovician to Silurian, 422 to 487 million years old. About 8 mi of the line.
Metaclastic. Age: Silurian, 422 to 445 million years old. About 5 mi of the line.
Granite, pegmatite. Age: Ordovician to Silurian, 422 to 487 million years old. About 4 mi of the line.
Granite. Age: Early Devonian to Late Devonian, 359 to 422 million years old. About 3 mi of the line.
Schist, granofels. Age: Ordovician to Silurian, 422 to 487 million years old. About 3 mi of the line.
Granodiorite. Age: Silurian, 428 to 445 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.
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 Pelham reaches the Atlantic Ocean by way of the Merrimack: about 50 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Pelham; river miles along the main stem, rounded.
Pelham has a hot-summer humid continental climate. Summer afternoons average 84° in July; winter nights fall to about 13° in January. A normal year brings about 67 inches of snow; with the rain, that comes to about 46 inches of water.
On November 14 Pelham normally reaches 50° and falls to 29°. The record high is 64°, in 2010; the record low 8°, in 1986. The most rain on this date, 0.77 in, fell in 2018.
Normals 1991–2020 and records since 1948 at Hudson 1 SSE, 6 miles northwest. NOAA, through RCC-ACIS.
