The Somersworth 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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Mostly sunny; warmer
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3° on Nov. 17, 1967, the coldest reading for this week of the year since 1893. Next is 6° in 1933.
Somersworth’s center stands about 240 ft above sea level. Within three miles the land runs from 100 ft to 410 ft, a difference of 310 ft: rolling country. The highest named summit within 15 miles is Blue Job Mountain, about 1,340 ft, 14 miles west-northwest.
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 8 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 47×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sandstone, mudstone. Age: Silurian to Devonian, 359 to 445 million years old. About 8 mi of the line.
Metasandstone, phyllite. Age: Ordovician to Silurian, 422 to 487 million years old. About 5 mi of the line.
Granofels, biotite-schist. Age: Ordovician to Silurian, 422 to 487 million years old. About 3 mi of the line.
Schist, phyllite. Age: Neoproterozoic to Devonian, 359 to 1,000 million years old. About 2 mi of the line.
Phyllite, quartzite, mica-schist. Age: Ordovician to Silurian, 422 to 487 million years old. About 2 mi of the line.
Diorite, gabbro. Age: Early Devonian, 394 to 422 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. 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 Somersworth reaches the Atlantic Ocean by way of Tates Brook, the Salmon Falls and the Piscataqua: about 20 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Somersworth; river miles along the main stem, rounded.
Somersworth has a warm-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 15° in January. A normal year brings about 39 inches of snow; with the rain, that comes to about 45 inches of water.
On November 14 Somersworth normally reaches 49° and falls to 31°. The record high is 71°, in 1989; the record low 6°, in 2019. The most rain on this date, 2.14 in, fell in 1937.
Normals 1991–2020 and records since 1893 at Durham, 9 miles south-southwest, 160 ft lower. NOAA, through RCC-ACIS.
