The Monrovia 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.
4° on Nov. 17, 1959, the coldest reading for this week of the year since 1871. Next is 8° in 2019.
Monrovia’s center stands about 800 ft above sea level. Within three miles the land runs from 730 ft to 920 ft, a difference of 190 ft: gently rolling country. The highest named summit within 15 miles is Mount Nebo, about 960 ft, 14 miles south-southeast.
Under the town center the state geologic map shows Borden Group (siltstone), from the Carboniferous, 324 to 359 million years old.
Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 50×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.
Siltstone. Age: Carboniferous, 324 to 359 million years old. About 24 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 Monrovia reaches the Gulf of America by way of Sycamore Creek, the White River, Big Bayou, the Wabash River Old Channel, the Old Channel Wabash, the Ohio and the Mississippi: about 1,380 river miles.
970 miles of the trip are on the Mississippi.
Traced down the USGS NHDPlus V2.1 river network from the Census center point of Monrovia; river miles along the main stem, rounded.
Monrovia has a hot-summer humid continental climate. Summer afternoons average 85° in July; winter nights fall to about 21° in January. A normal year brings about 26 inches of snow; with the rain, that comes to about 44 inches of water.
On November 14 Monrovia normally reaches 52° and falls to 35°. The record high is 76°, in 1971; the record low 11°, in 1986. The most rain on this date, 4.15 in, fell in 1993.
Normals 1991–2020 and records since 1871 from the Indianapolis Area threaded record (Indianapolis International Airport, 15 miles northeast). NOAA, through RCC-ACIS.