The Riverhead 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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78° on Nov. 15, 1993, the hottest reading for this week of the year since 1938. Next is 72° in 1990.
Riverhead’s center stands about 18 ft above sea level. Within three miles the land runs from 0 ft to 210 ft, a difference of 210 ft: rolling country. The highest named summit within 15 miles is Bald Hill, about 290 ft, 4 miles southwest.
Under the town center the state geologic map shows Monmouth Group, Matawan Group and Magothy Formation (clay, sand, gravel), from the Late Cretaceous, 66 to 100 million years old.
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.
Clay, sand, gravel. Age: Late Cretaceous, 66 to 100 million years old. About 18 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 Riverhead runs straight into Long Island Sound and the Atlantic Ocean.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Riverhead; river miles along the main stem, rounded.
Riverhead has a humid subtropical climate. Summer afternoons average 84° in July; winter nights fall to about 26° in January. About 47 inches of rain fall in a normal year.
On November 14 Riverhead normally reaches 54° and falls to 40°. The record high is 73°, in 1993; the record low 23°, in 2019. The most rain on this date, 1.62 in, fell in 1972.
Normals 1991–2020 and records since 1938 at Riverhead Research Farm, 4 miles northwest. NOAA, through RCC-ACIS.
