The Bethlehem 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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77° on Nov. 15, 1993, the hottest reading for this week of the year since 1912. Next is 74° in 1973.
Bethlehem’s center stands about 350 ft above sea level. Within three miles the land runs from 210 ft to 860 ft, a difference of 650 ft: hilly country. The highest named summit within 15 miles is Sandstone Ridge, about 1,040 ft, 14 miles west-northwest.
Under the town center the state geologic map shows Allentown Formation (dolostone, limestone), from the Cambrian, 487 to 542 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 22×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Dolostone, limestone. Age: Cambrian, 487 to 542 million years old. About 9 mi of the line.
Limestone, dolostone. Age: Ordovician, 445 to 487 million years old. About 6 mi of the line.
Gneiss. Age: Precambrian. About 3 mi of the line.
Hornblende-gneiss. Age: Precambrian. About 2 mi of the line.
Dolostone. Age: Early Cambrian to Middle Cambrian, 497 to 542 million years old. About 2 mi of the line.
Dolostone. Age: Ordovician, 445 to 487 million years old. About 0.7 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 Bethlehem reaches Delaware Bay and the Atlantic Ocean by way of the Lehigh and the Delaware: about 160 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Bethlehem; river miles along the main stem, rounded.
Bethlehem has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 22° in January. A normal year brings about 33 inches of snow; with the rain, that comes to about 47 inches of water.
On November 14 Bethlehem normally reaches 54° and falls to 34°. The record high is 73°, in 1993; the record low 17°, in 1986. The most rain on this date, 2.41 in, fell in 1972.
Normals 1991–2020 and records since 1912 from the Allentown Area threaded record (Allentown Lehigh Valley International Airport, 4 miles west-northwest). NOAA, through RCC-ACIS.
