The Hermiston 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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76° on Nov. 14, 1999, the hottest reading for this week of the year since 1971. Next is 72° in 2001.
Hermiston’s center stands about 460 ft above sea level. Within three miles the land runs from 430 ft to 660 ft, a difference of 230 ft: rolling country. The highest named summit within 15 miles is Service Buttes, about 1,680 ft, 13 miles south.
Under the town center the state geologic map shows Glaciofluvial, lacustrine, and pediment sedimentary deposits (silt, sand, gravel), from the Pleistocene, less than 2.6 million years old.
The section below crosses 4 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.
Silt, sand, gravel. Age: Pleistocene, less than 2.6 million years old. About 14 mi of the line.
Silt, sand. Age: Pleistocene to Holocene, less than 2.6 million years old. About 5 mi of the line.
Silt. Age: Pleistocene, less than 2.6 million years old. About 4 mi of the line.
Silt, sand. Age: Holocene, less than 12,000 years old. About 0.3 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 Hermiston reaches the Pacific Ocean by way of the Hermiston Ditch, the Umatilla and the Columbia: about 290 river miles.
Lake on the way: Lake Umatilla.
210 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Hermiston; river miles along the main stem, rounded.
Hermiston has a cold semi-arid climate. Summer afternoons average 91° in July; winter nights fall to about 29° in January. About 9 inches of rain fall in a normal year, with about 4 inches of snow.
On November 14 Hermiston normally reaches 52° and falls to 33°. The record high is 76°, in 1999; the record low 8°, in 1978. The most rain on this date, 0.30 in, fell in 2024.
Normals 1991–2020 and records since 1971 at Boardman, 19 miles west, 180 ft lower. NOAA, through RCC-ACIS.
