The Monroe 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.
Chance of showers
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4.52 inches of rain fell in two days, the most for this week of the year since records began in 1892. The next wettest, 4.46 inches, fell in 1950.
Monroe’s center stands about 300 ft above sea level. Within three miles the land runs from 260 ft to 940 ft, a difference of 680 ft: hilly country. The highest named summit within 15 miles is Green Peak, about 2,730 ft, 9 miles west-northwest.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 8×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Clay, silt, sand. Age: Pleistocene, less than 2.6 million years old. About 8 mi of the line.
Sandstone. Age: Middle Eocene, 38 to 48 million years old. About 7 mi of the line.
Sand, gravel, silt. Age: Holocene, less than 12,000 years old. About 6 mi of the line.
Mudstone. Age: Middle Eocene to Late Eocene, 34 to 48 million years old. About 3 mi of the line.
Gabbro. Age: Oligocene, 23 to 34 million years old. About 1 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 Monroe reaches the Pacific Ocean by way of the Long Tom, the Willamette and the Columbia: about 250 river miles.
Lake on the way: Willamette Falls Hydroelectric Power Reservoir.
100 miles of the trip are on the Columbia.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Monroe; river miles along the main stem, rounded.
Monroe has a warm-summer Mediterranean climate. Summer afternoons average 84° in July; winter nights fall to about 34° in December. About 41 inches of rain fall in a normal year.
On November 14 Monroe normally reaches 54° and falls to 38°. The record high is 68°, in 1912; the record low 14°, in 1978. The most rain on this date, 1.70 in, fell in 1941.
Normals 1991–2020 and records since 1892 from the Eugene Area threaded record (Eugene-Mahlon Sweet Field, 13 miles south-southeast). NOAA, through RCC-ACIS.
