The Harahan 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.
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27° on Nov. 17, 1970, the coldest reading for this week of the year since 1946. Next is 28° in 1968.
Harahan’s center stands about 15 ft above sea level. Within three miles the land runs from 0 ft to 30 ft, a difference of 30 ft: nearly flat ground. Open water lies within three miles.
Under the town center the state geologic map shows Natural Levees (silt, clay), from the Holocene, less than 12,000 years old.
The section below crosses 3 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.
Clay. Age: Holocene, less than 12,000 years old. About 8 mi of the line.
Clay. Age: Holocene, less than 12,000 years old. About 7 mi of the line.
Silt, clay. Age: Holocene, less than 12,000 years old. About 5 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.
Harahan has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 46° in January. About 63 inches of rain fall in a normal year.
On November 14 Harahan normally reaches 71° and falls to 54°. The record high is 84°, in 2011; the record low 33°, in 1969. The most rain on this date, 1.43 in, fell in 1998.
Normals 1991–2020 and records since 1946 from the New Orleans Area threaded record (New Orleans Airport, 6 miles northwest). NOAA, through RCC-ACIS.
