[6][7] Fish Hole Creek, which flows through the community, meets the South Fork Sprague River slightly north of Bly.

[6][7] This region experiences warm (but not hot) and dry summers, with no average monthly temperatures above 71.6 °F (22.0 °C).

[8] The name Bly comes from the Klamath word p'lai, meaning 'up' or 'high', referring to its location at the upper Sprague River.

[10] A history published in 1905 referred to the surrounding area as the "precinct" or the "valley" and estimated its total population at 750.

[10] The chief products of the valley at that time included cattle, horses, mules, and a few sheep, as well as oats, clover, and hay.

[11][12] Bly is also the site of the only fatalities of World War II in the continental U.S. due to an enemy balloon bomb attack.