Forest Glen is located on California State Route 36, 14.5 miles (23.3 km) south-southwest of Hayfork.

With a population of around 10 permanent residents and 20 seasonal Forest Service cabin owners, visitors often drive right through in 30 seconds, little realizing there was a town.

In 1913, Arthur H. Jeans built a waystation for travellers on the new Red Bluff-Eureka road, now known as State Route 36, at Forest Glen, then known as Auto Rest.

A post office called Auto Rest ran from September 13, 1917, until March 9, 1920, when the name was changed to Forest Glen.

[3] Forest Glen is situated at the base of South Fork Mountain, the longest continuous ridge line in North America.

Forest Glen is reputed to be one of the wettest places in Trinity County, with over 60 inches of precipitation over the weather station's period of record.

Forest Glen has seen frost every month of the year, but the 30% chance date in the spring is in mid-June, and in the fall it is mid-to-late-September.

If a similar event were to happen today, the effects would likely be much less devastating as nearly all logging in the watershed has ceased, and has not resumed in the past 30 years.