Yellowstone National Park reopened the Firehole, Madison, and Gibbon rivers to fishing during morning hours. Anglers may use these waters from sunrise until 2 p.m. while afternoons remain closed to protect fish from heat.
via Snacks News

Recent cooling and forecasted rain allow for these rivers to reopen to fishing during the morning and early afternoon hours. The full closures had been in place since July because water temperatures over 68 degrees were threatening local fish populations. Staff will continue to monitor conditions to determine if further restrictions are needed as temperatures fluctuate.