The Sinai 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.
Sunny
Mostly sunny; warmer
Mostly sunny
Partly cloudy
Partly cloudy
Partly cloudy; cooler
Showers likely
−17° on Nov. 14, 1959, the coldest reading for this week of the year since 1893. Next is −12° in 1997.
Sinai’s center stands about 1,780 ft above sea level. Within three miles the land runs from 1,680 ft to 1,810 ft, a difference of 130 ft: gently rolling country.
Under the town center the state geologic map shows Pierre Shale (shale, bentonite), from the Late Cretaceous, 66 to 100 million years old.
The section below crosses 2 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 64×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Shale, bentonite. Age: Late Cretaceous, 66 to 100 million years old. About 20 mi of the line.
Chalk, marlstone, shale. Age: Late Cretaceous, 66 to 100 million years old. About 4 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 Sinai reaches the Gulf of America by way of Lake Campbell Outlet, the Big Sioux, the Missouri and the Mississippi: about 2,170 river miles.
1,170 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Sinai; river miles along the main stem, rounded.
Sinai has a warm-summer humid continental climate. Summer afternoons average 82° in July; winter nights fall to about 3° in January. A normal year brings about 36 inches of snow; with the rain, that comes to about 25 inches of water.
On November 14 Sinai normally reaches 42° and falls to 22°. The record high is 74°, in 1999; the record low −17°, in 1959. The most rain on this date, 0.39 in, fell in 1983.
Normals 1991–2020 and records since 1893 at Brookings 2 NE, 15 miles east-northeast, 140 ft lower. NOAA, through RCC-ACIS.
