The Swan Valley 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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67° on Nov. 14, 2025, the hottest reading for this week of the year since 1960. Next is 66° in 1999.
Swan Valley’s center stands about 5,320 ft above sea level. Within three miles the land runs from 5,260 ft to 6,640 ft, a difference of 1,380 ft: steep hill country. The highest named summit within 15 miles is Mount Baird, about 9,950 ft, 14 miles east-southeast.
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 4×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Rhyolite. Age: Late Miocene to Late Pliocene, 3 to 6.6 million years old. About 7 mi of the line.
Limestone, dolostone. Age: Cambrian to Ordovician, 445 to 542 million years old. About 4 mi of the line.
Mixed-clastic, volcanic. Age: Early Miocene to Pleistocene, 2 to 16 million years old. About 3 mi of the line.
Basalt. Age: Late Pliocene to Pleistocene, less than 3 million years old. About 3 mi of the line.
Gravel. Age: Quaternary, less than 2.6 million years old. About 2 mi of the line.
Gravel, sand, silt. Age: Quaternary, less than 2.6 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. 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 Swan Valley reaches the Pacific Ocean by way of Rainey Creek, the Snake and the Columbia: about 1,200 river miles.
Lakes on the way: American Falls Reservoir, Lake Umatilla, Brownlee Reservoir and Cove Arm Lake.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Swan Valley; river miles along the main stem, rounded.
Swan Valley has a warm-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 11° in January. About 20 inches of rain fall in a normal year.
On November 14 Swan Valley normally reaches 44° and falls to 21°. The record high is 67°, in 2025; the record low 2°, in 1978. The most rain on this date, 0.68 in, fell in 2010.
Normals 1991–2020 and records since 1960 at Swan Valley, 3 miles east-southeast. NOAA, through RCC-ACIS.
