The Callahan 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 cloudy
Partly cloudy
Chance of showers
Partly cloudy
Partly cloudy
3.30 inches of rain fell in two days, the most for this week of the year since records began in 1871. The next wettest, 2.79 inches, fell in 1947.
Callahan’s center stands about 30 ft above sea level. Within three miles the land runs from 10 ft to 80 ft, a difference of 70 ft: gently rolling country.
Under the town center the state geologic map shows Undifferentiated sediments (sand, clay), from the Pleistocene to Holocene, less than 2.6 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.
Sand, clay. Age: Pleistocene to Holocene, less than 2.6 million years old. About 14 mi of the line.
Sand. Age: Late Pliocene, 2.6 to 3.6 million years old. About 10 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 Callahan reaches the Atlantic Ocean by way of Alligator Creek and the Nassau: about 45 river miles.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Callahan; river miles along the main stem, rounded.
Callahan has a humid subtropical climate. Summer afternoons average 92° in July; winter nights fall to about 43° in January. About 53 inches of rain fall in a normal year.
On November 14 Callahan normally reaches 74° and falls to 51°. The record high is 84°, in 2008; the record low 31°, in 1984. The most rain on this date, 2.21 in, fell in 1941.
Normals 1991–2020 and records since 1871 from the Jacksonville Area threaded record (Jacksonville International Airport, 10 miles east-southeast). NOAA, through RCC-ACIS.
