The Allen 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.
Mostly cloudy
Showers likely; cooler
Mostly sunny; warmer
Sunny
Partly cloudy
Mostly cloudy
Partly cloudy
84° on Nov. 16, 2025, the hottest reading for this week of the year since 1947. Next is 83° in 2016.
Allen’s center stands about 870 ft above sea level. Within three miles the land runs from 740 ft to 930 ft, a difference of 190 ft: gently rolling country.
Under the town center the state geologic map shows Terrace Deposits (coarse-detrital, fine-detrital), from the Pleistocene, less than 2.6 million years old.
The section below crosses 11 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 58×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Coarse-detrital, fine-detrital. Age: Pleistocene, less than 2.6 million years old. About 5 mi of the line.
Fine-detrital. Age: Holocene, less than 12,000 years old. About 4 mi of the line.
Sandstone, shale. Age: Carboniferous, 299 to 324 million years old. About 3 mi of the line.
Shale, sandstone. Age: Carboniferous, 299 to 324 million years old. About 3 mi of the line.
Sandstone. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
Shale, sandstone, conglomerate. Age: Carboniferous, 299 to 324 million years old. About 2 mi of the line.
From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 5 smaller units along the line are not listed.
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 Allen reaches the Gulf of America by way of Town Branch, Little Sandy Creek, Muddy Boggy Creek, the Red River, the Atchafalaya and the Lower Atchafalaya: about 880 river miles.
590 miles of the trip are on the Red River.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Allen; river miles along the main stem, rounded.
Allen has a humid subtropical climate. Summer afternoons average 93° in August; winter nights fall to about 28° in January. About 46 inches of rain fall in a normal year, with about 3 inches of snow.
Normals 1991–2020 and records since 1947 at Centrahoma 2 ESE, 20 miles south-southeast, 160 ft lower. NOAA, through RCC-ACIS.
