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.
Partly cloudy
Mostly sunny; warmer
Mostly sunny
Mostly sunny
Mostly sunny
Mostly sunny
Mostly sunny
72° on Nov. 12, 2022, the hottest reading for this week of the year since 1996. Next is 67° in 2005.
Portsmouth’s center stands about 140 ft above sea level. Within three miles the land runs from 0 ft to 270 ft, a difference of 270 ft: rolling country. Open water lies within three miles. The highest named summit within 15 miles is Andrews Hill, about 420 ft, 15 miles west-northwest.
Under the town center the state geologic map shows Narragansett Bay Group - Rhode Island Formation, from the Carboniferous, 299 to 324 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.
Age: Carboniferous, 299 to 324 million years old. About 5 mi of the line.
Granite. Age: Neoproterozoic, 600 to 601 million years old. About 5 mi of the line.
Granite. Age: Neoproterozoic, 542 to 1,000 million years old. About 3 mi of the line.
Granite. Age: Neoproterozoic, 542 to 1,000 million 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.
Rain that falls on Portsmouth runs straight into Narragansett Bay and the Atlantic Ocean.
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 hot-summer humid continental climate. Summer afternoons average 80° in July; winter nights fall to about 24° in January. About 42 inches of rain fall in a normal year.
On November 14 Portsmouth normally reaches 53° and falls to 38°. The record high is 67°, in 2005; the record low 20°, in 2019. The most rain on this date, 0.64 in, fell in 2000.
Normals 1991–2020 and records since 1996 at Newport State Airport, 5 miles south-southwest. NOAA, through RCC-ACIS.
