The St. Johns 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.
Chance of showers
Mostly sunny
Mostly sunny
Chance of showers
Sunny; cooler
Partly cloudy
Mostly sunny; cooler
80° on Nov. 12, 1967, the hottest reading for this week of the year since 1901. Next is 79° in 1927.
St. Johns’s center stands about 5,730 ft above sea level. Within three miles the land runs from 5,630 ft to 6,060 ft, a difference of 430 ft: hilly country. The highest named summit within 15 miles is South Mountain, about 6,070 ft, 14 miles northwest.
The section below crosses 5 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 16×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Conglomerate, sandstone. Age: Early Miocene to Pleistocene, 2 to 16 million years old. About 11 mi of the line.
Mudstone. Age: Late Triassic, 210 to 230 million years old. About 11 mi of the line.
Sandstone, mudstone. Age: Middle Triassic to Late Triassic, 230 to 245 million years old. About 1 mi of the line.
Gravel, sand. Age: Late Pliocene to Pleistocene, 0.8 to 3 million years old. About 0.9 mi of the line.
Sand, silt, clay. Age: Pleistocene to Holocene, less than 2 million years old. About 0.5 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.
A raindrop that lands in St. Johns reaches the Gulf of California by way of the Little Colorado and the Colorado: about 1,020 river miles.
Lakes on the way: Lake Mead, Lake Mohave and Lake Havasu.
300 miles of the trip are on the Little Colorado.
Often dry. About 30% of the way is mapped as streams that run only after rain or snowmelt; the water makes the whole trip in floods.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of St. Johns; river miles along the main stem, rounded.
St. Johns has a cold semi-arid climate. Summer afternoons average 91° in July; winter nights fall to about 20° in December. A normal year brings about 6 inches of snow; with the rain, that comes to about 9 inches of water.
On November 14 St. Johns normally reaches 61° and falls to 28°. The record high is 78°, in 1967; the record low 8°, in 1945. The most rain on this date, 0.34 in, fell in 1968.
Normals 1991–2020 and records since 1901 at Saint Johns, here. NOAA, through RCC-ACIS.
