The Derry 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.
Mostly cloudy
Mostly cloudy; warmer
Mostly cloudy
Partly cloudy
Sunny
Mostly sunny
Mostly sunny
4.45 inches of rain fell in two days, the most for this week of the year since records began in 1980. The next wettest, 2.62 inches, fell in 2015.
Derry’s center stands about 1,190 ft above sea level. Within three miles the land runs from 1,050 ft to 2,360 ft, a difference of 1,310 ft: steep hill country. The highest named summit within 15 miles is Pea Vine Hill, about 2,940 ft, 13 miles southeast.
Under the town center the state geologic map shows Glenshaw Formation (shale), from the Carboniferous, 299 to 324 million years old.
The section below crosses 7 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 11×. 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, clastic. Age: Carboniferous, 299 to 324 million years old. About 9 mi of the line.
Shale. Age: Carboniferous, 299 to 324 million years old. About 6 mi of the line.
Limestone, shale, sandstone. Age: Carboniferous, 299 to 324 million years old. About 4 mi of the line.
Sandstone, conglomerate. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
Sandstone. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
Shale, siltstone, sandstone. Age: Carboniferous, 324 to 359 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. 1 smaller unit 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 Derry reaches the Gulf of America by way of Stony Run, the Conemaugh, the Kiskiminetas, the Allegheny, the Ohio and the Mississippi: about 2,020 river miles.
970 miles of the trip are on the Ohio.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Derry; river miles along the main stem, rounded.
Derry has a warm-summer humid continental climate. Summer afternoons average 83° in July; winter nights fall to about 19° in January. About 43 inches of rain fall in a normal year.
On November 14 Derry normally reaches 52° and falls to 30°. The record high is 74°, in 1994; the record low 12°, in 2019. The most rain on this date, 1.13 in, fell in 1995.
Normals 1991–2020 and records since 1980 at Loyalhanna Lake, 12 miles northwest, 200 ft lower. NOAA, through RCC-ACIS.
