The Boulder 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
Partly cloudy
Partly cloudy
Showers likely
Mostly sunny; cooler
Showers likely
Showers likely
−22° on Nov. 13, 2014, the coldest reading for this week of the year since 1989. Next is −21° in 2000.
Boulder’s center stands about 7,020 ft above sea level. Within three miles the land runs from 6,930 ft to 7,170 ft, a difference of 240 ft: rolling country. The highest named summit within 15 miles is Aspen Butte, about 9,470 ft, 14 miles east.
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 7×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Oil-shale, marlstone, mudstone. Age: Eocene, 34 to 56 million years old. About 14 mi of the line.
Granite. Age: Archean. About 4 mi of the line.
Gravel. Age: Pleistocene to Holocene, less than 2.6 million years old. About 3 mi of the line.
Sand, gravel, boulders. Age: Pleistocene to Holocene, less than 2.6 million years old. About 1 mi of the line.
Clay, silt, sand. Age: Pleistocene to Holocene, less than 2.6 million years old. About 1 mi of the line.
Dolostone, limestone. Age: Middle Cambrian to Late Ordovician, 445 to 521 million 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 Boulder reaches the Gulf of California by way of the East Fork, the New Fork, the Green River and the Colorado: about 1,640 river miles.
Lakes on the way: Lake Mead, Lake Powell, Flaming Gorge Reservoir and Lake Mohave.
410 miles of the trip are on the Green River.
Seldom reaches the sea. Dams and canals now take nearly all of the Colorado before its old delta in Mexico.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Boulder; river miles along the main stem, rounded.
Boulder has a warm-summer humid continental climate. Summer afternoons average 81° in July; winter nights fall to about −7° in January. A normal year brings about 42 inches of snow; with the rain, that comes to about 9 inches of water.
On November 14 Boulder normally reaches 42° and falls to 9°. The record high is 62°, in 1999; the record low −18°, in 2000. The most rain on this date, 0.37 in, fell in 2006.
Normals 1991–2020 and records since 1989 at Boulder Rearing Station, 3 miles south-southeast. NOAA, through RCC-ACIS.
