The Iona 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.
Partly cloudy
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Partly cloudy
Showers likely; cooler
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Showers likely
Chance of showers
70° on Nov. 15, 1999, the hottest reading for this week of the year since 1952. Next is 66° in 1953.
Iona’s center stands about 4,790 ft above sea level. Within three miles the land runs from 4,730 ft to 5,440 ft, a difference of 710 ft: hilly country. The highest named summit within 15 miles is Big Horse Butte, about 6,500 ft, 15 miles southeast.
Under the town center the state geologic map shows Alluvial deposits (gravel, sand, silt), from the Quaternary, less than 2.6 million years old.
The section below crosses 3 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 12×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Gravel, sand, silt. Age: Quaternary, less than 2.6 million years old. About 14 mi of the line.
Rhyolite. Age: Late Miocene to Late Pliocene, 3 to 6.6 million years old. About 10 mi of the line.
Gravel. Age: Quaternary, less than 2.6 million years old. About 0.5 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 Iona reaches the Pacific Ocean by way of Sand Creek, the Reservation Canal, the Blackfoot, the Snake and the Columbia: about 1,120 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 Iona; river miles along the main stem, rounded.
Iona has a warm-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 16° in January. About 14 inches of rain fall in a normal year.
On November 14 Iona normally reaches 44° and falls to 26°. The record high is 64°, in 1999; the record low −4°, in 1978. The most rain on this date, 0.55 in, fell in 1957.
Normals 1991–2020 and records since 1952 at Idaho Falls - Kifi, 4 miles west-southwest. NOAA, through RCC-ACIS.
