The Helena 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
Partly cloudy; warmer
Mostly sunny
Sunny
Mostly sunny
Partly cloudy
Mostly sunny
21° on Nov. 11, 2025, the coldest reading for this week of the year since 1995. Next is 22° in 1997.
Helena’s center stands about 420 ft above sea level. Within three miles the land runs from 400 ft to 670 ft, a difference of 270 ft: rolling country. The highest named summit within 15 miles is Johnson Mountain, about 860 ft, 5 miles east-northeast.
Under the town center the state geologic map shows Rome Formation (mudstone, shale, siltstone), from the Cambrian, 487 to 542 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 26×. 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, siltstone, sandstone. Age: Carboniferous, 299 to 324 million years old. About 8 mi of the line.
Sandstone, shale, siltstone. Age: Carboniferous, 299 to 324 million years old. About 7 mi of the line.
Shale. Age: Carboniferous, 324 to 359 million years old. About 3 mi of the line.
Shale. Age: Carboniferous, 324 to 359 million years old. About 2 mi of the line.
Limestone, dolostone. Age: Cambrian to Ordovician, 445 to 542 million years old. About 1 mi of the line.
Limestone. Age: Ordovician, 445 to 487 million years old. About 1 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 Helena reaches Mobile Bay and the Gulf of America by way of the Cahaba, the Alabama and the Mobile: about 380 river miles.
200 miles of the trip are on the Alabama.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Helena; river miles along the main stem, rounded.
Helena has a humid subtropical climate. Summer afternoons average 91° in July; winter nights fall to about 36° in January. About 56 inches of rain fall in a normal year.
On November 14 Helena normally reaches 66° and falls to 43°. The record high is 79°, in 2005; the record low 26°, in 2014. The most rain on this date, 1.71 in, fell in 1998.
Normals 1991–2020 and records since 1995 at Alabaster Shelby Co Airport Asos, 9 miles south-southeast, 150 ft higher. NOAA, through RCC-ACIS.
