The Rillito 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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94° on Nov. 12, 1999, the hottest reading for this week of the year since 1982. Next is 90° in 2016.
Rillito’s center stands about 2,050 ft above sea level. Within three miles the land runs from 2,010 ft to 2,370 ft, a difference of 360 ft: rolling country. The highest named summit within 15 miles is Table Mountain, about 6,150 ft, 15 miles east.
Under the town center the state geologic map shows Holocene river alluvium (sand, gravel), from the Holocene, less than 10,000 years old.
The section below crosses 4 rock units mapped at the surface.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 8×. 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, silt, clay. Age: Pleistocene to Holocene, less than 2 million years old. About 16 mi of the line.
Granite, granodiorite, diorite. Age: Late Oligocene to Middle Miocene, 14 to 26 million years old. About 5 mi of the line.
Granite, granodiorite, diorite. Age: Late Cretaceous to Early Eocene, 50 to 82 million years old. About 2 mi of the line.
Sand, gravel. Age: Holocene, less than 10,000 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.
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.
Rillito has a hot desert climate. Summer afternoons average 102° in June; winter nights fall to about 39° in January. About 11 inches of rain fall in a normal year.
On November 14 Rillito normally reaches 76° and falls to 47°. The record high is 90°, in 1999; the record low 32°, in 1985. The most rain on this date, 0.55 in, fell in 2011.
Normals 1991–2020 and records since 1982 at Tucson 17 NW, 11 miles south-southwest, 510 ft higher. NOAA, through RCC-ACIS.
