The Arimo 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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66° on Nov. 15, 2025, the hottest reading for this week of the year since 1895. Next is 65° in 2016.
Arimo’s center stands about 4,750 ft above sea level. Within three miles the land runs from 4,630 ft to 5,570 ft, a difference of 940 ft: steep hill country. The highest named summit within 15 miles is Bonneville Peak, about 9,250 ft, 14 miles north.
Under the town center the state geologic map shows Lake Bonneville deposits (coarse-detrital, fine-detrital), from the Pleistocene to Holocene, less than 33,000 years old.
The section below crosses 6 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 5×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Limestone, dolostone. Age: Cambrian to Ordovician, 445 to 542 million years old. About 7 mi of the line.
Silt. Age: Pleistocene, less than 2.6 million years old. About 5 mi of the line.
Coarse-detrital, fine-detrital. Age: Pleistocene to Holocene, less than 33,000 years old. About 4 mi of the line.
Gravel, sand, silt. Age: Quaternary, less than 2.6 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.
Gravel. 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.
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 Arimo reaches the Pacific Ocean by way of Marsh Creek, the Portneuf, the Snake and the Columbia: about 1,110 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 Arimo; river miles along the main stem, rounded.
Arimo has a warm-summer humid continental climate. Summer afternoons average 89° in July; winter nights fall to about 14° in January. About 16 inches of rain fall in a normal year.
Normals 1991–2020 and records since 1895 at Downey, 10 miles south-southeast, 120 ft higher. NOAA, through RCC-ACIS.
