The Jefferson 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
Showers likely
Chance of showers
Chance of showers
Chance of showers
Partly cloudy
Partly cloudy
70° on Nov. 13, 1999, the hottest reading for this week of the year since 1892. Next is 68° in 1930.
Jefferson’s center stands about 250 ft above sea level. Within three miles the land runs from 200 ft to 510 ft, a difference of 310 ft: rolling country. The highest named summit within 15 miles is Vineyard Mountain, about 1,540 ft, 14 miles west-southwest.
Under the town center the state geologic map shows Lacustrine and fluvial sedimentary rocks (clay, silt, sand), from the Pleistocene, less than 2.6 million years old.
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 27×. 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, boulders, clay. Age: Pleistocene to Holocene, less than 2.6 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.
Basalt. Age: Early Miocene to Middle Miocene, 12 to 23 million years old. About 5 mi of the line.
Clay, silt, sand. Age: Pleistocene, less than 2.6 million years old. About 4 mi of the line.
Sandstone. Age: Oligocene to Early Miocene, 16 to 34 million years old. About 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 Jefferson reaches the Pacific Ocean by way of the Santiam, the Willamette and the Columbia: about 220 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 Jefferson; river miles along the main stem, rounded.
Jefferson has a warm-summer Mediterranean climate. Summer afternoons average 84° in July; winter nights fall to about 35° in December. About 40 inches of rain fall in a normal year.
On November 14 Jefferson normally reaches 54° and falls to 39°. The record high is 68°, in 2001; the record low 12°, in 1955. The most rain on this date, 3.00 in, fell in 1896.
Normals 1991–2020 and records since 1892 from the Salem Area threaded record (Salem Airport (Mcnary Field), 13 miles north). NOAA, through RCC-ACIS.
