The Portsmouth 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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85° on Nov. 11, 2020, the hottest reading for this week of the year since 1874. Next is 84° in 1993.
Portsmouth’s center stands about 13 ft above sea level. Within three miles the land runs from 0 ft to 50 ft, a difference of 50 ft: nearly flat ground. Open water lies within three miles.
Under the town center the state geologic map shows Tabb Formation; Lynnhaven Member (sand, silt), from the Quaternary, less than 2.6 million years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Sand, silt. Age: Quaternary, less than 2.6 million years old. About 10 mi of the line.
Sand. Age: Quaternary, less than 2.6 million years old. About 3 mi of the line.
Peat, clay, sand. Age: Holocene, less than 12,000 years old. About 3 mi of the line.
Sand. Age: Holocene, less than 12,000 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.
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 Portsmouth reaches Chesapeake Bay and the Atlantic Ocean by way of Lilly Creek, the Western Branch Elizabeth, the Elizabeth and the James: about 11 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Portsmouth; river miles along the main stem, rounded.
Portsmouth has a humid subtropical climate. Summer afternoons average 90° in July; winter nights fall to about 34° in January. A normal year brings about 6 inches of snow; with the rain, that comes to about 49 inches of water.
On November 14 Portsmouth normally reaches 62° and falls to 45°. The record high is 80°, in 1993; the record low 24°, in 1976. The most rain on this date, 2.37 in, fell in 1945.
Normals 1991–2020 and records since 1874 from the Norfolk Area threaded record (Norfolk International Airport, 10 miles east-northeast). NOAA, through RCC-ACIS.
