The Harrisburg 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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9° on Nov. 17, 1959, the coldest reading for this week of the year since 1888. Next is 10° in 1986.
Harrisburg’s center stands about 390 ft above sea level. Within three miles the land runs from 350 ft to 450 ft, a difference of 100 ft: gently rolling country. The highest named summit within 15 miles is Williams Hill, about 1,100 ft, 11 miles south-southeast.
Under the town center the state geologic map shows Shelburn-Patoka Formations undivided (shale, limestone), from the Late Pennsylvanian, 304 to 307 million years old.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 38×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 10 mi of the line.
Shale, sandstone, coal. Age: Middle Pennsylvanian to Late Pennsylvanian, 304 to 315 million years old. About 4 mi of the line.
Shale, sandstone. Age: Early Pennsylvanian to Middle Pennsylvanian, 307 to 324 million years old. About 4 mi of the line.
Shale, sandstone, limestone. Age: Late Pennsylvanian, 304 to 307 million years old. About 3 mi of the line.
Shale, sandstone. Age: Early Pennsylvanian, 315 to 324 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.
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 Harrisburg reaches the Gulf of America by way of the Middle Fork Saline, the Saline, the Ohio and the Mississippi: about 1,120 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Harrisburg; river miles along the main stem, rounded.
Harrisburg has a humid subtropical climate. Summer afternoons average 89° in July; winter nights fall to about 24° in January. About 48 inches of rain fall in a normal year.
On November 14 Harrisburg normally reaches 58° and falls to 37°. The record high is 80°, in 1999; the record low 10°, in 1986. The most rain on this date, 1.00 in, fell in 2024.
Normals 1991–2020 and records since 1888 at Harrisburg, here. NOAA, through RCC-ACIS.
