The Rocky Hill 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
Partly cloudy; warmer
Partly cloudy
Mostly sunny
Sunny
Mostly sunny
Mostly sunny
79° on Nov. 16, 1993, the hottest reading for this week of the year since 1893. Next is 76° in 2020.
Rocky Hill’s center stands about 110 ft above sea level. Within three miles the land runs from 50 ft to 380 ft, a difference of 330 ft: rolling country. The highest named summit within 15 miles is Sourland Mountain, about 640 ft, 6 miles northwest.
Under the town center the state geologic map shows Passaic Formation (siltstone), from the Late Triassic to Early Jurassic, 175 to 237 million years old.
The section below crosses 9 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 34×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Siltstone, shale. Age: Early Jurassic to Late Jurassic, 145 to 202 million years old. About 6 mi of the line.
Siltstone. Age: Late Triassic to Early Jurassic, 175 to 237 million years old. About 6 mi of the line.
Sand. Age: Late Cretaceous, 84 to 87 million years old. About 4 mi of the line.
Plutonic. Age: Jurassic, 145 to 202 million years old. About 2 mi of the line.
Siltstone-mudstone, sandstone-mudstone. Age: Late Triassic, 202 to 237 million years old. About 2 mi of the line.
Sand. Age: Late Cretaceous, 72 to 84 million years old. About 2 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 3 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 Rocky Hill reaches New York Harbor and the Atlantic Ocean by way of the Millstone and the Raritan: about 35 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Rocky Hill; river miles along the main stem, rounded.
Rocky Hill has a hot-summer humid continental climate. Summer afternoons average 87° in July; winter nights fall to about 23° in January. A normal year brings about 29 inches of snow; with the rain, that comes to about 50 inches of water.
On November 14 Rocky Hill normally reaches 56° and falls to 36°. The record high is 72°, in 1955; the record low 15°, in 1986. The most rain on this date, 0.81 in, fell in 1940.
Normals 1991–2020 and records since 1893 from the New Brunswick Area threaded record (New Brunswick 3 SE, 12 miles east-northeast). NOAA, through RCC-ACIS.
