The excellent conditions of late are met with change. The continued late summer heat with high freezing levels are helping the firn-snow line retreat just beyond optimal conditions and inducing rockfall. Guides in the Rockies and Columbias have been reporting rockfall events of various sizes. Most notably, a massive event on Mt. Bidle with accompanying dust cloud a few days ago. Popular zones that are changing quickly and seeing increased rockfall are the Bugaboo-Snowpatch col in the Columbia's and Mt. Lefroy in the Rockies.
Daytime heating and high freezing levels are something to be watchful of, but reducing your exposure to known rockfall zones in general may be the best approach as we transition out of optimal summer mountaineering conditions. The weather forecast shows, yet again, a period of clear and hot weather for the foreseeable future in both the Rockies and Columbias. The freezing levels are expected to be high.
Although rockfall is a significant hazard right now, glacier travel is surprisingly good for this time of year and coverage is still reasonable. We have enjoyed an unusual summer that provided us with excellent snow coverage late into the season. Now, as things change, tune your objectives so that you are not exposed to overhead rockfall fall hazard as a result of melting snow and ice.
ACMG Mountain Guide