While the average annual high is a pleasant 76 degrees Fahrenheit ( 24 Celsius), on hotter days trail temperatures can reach upwards of 110 degrees (43 Celsius). The average annual low is a cool 47 Fahrenheit (8 Celsius). The humidity levels at Havasupai are extremely low, so especially on those hotter days, keep the temperature in mind before heading off for long hikes.
While your hiking experience can definitely be determined by the day’s heat, swimming is pleasant year-round. The temperature of the water holes, creeks, and rivers is a relatively constant 70 degrees Fahrenheit (21 Celsius) year-round- perfect for taking a relaxing soak.
The Havasu Canyon is subject to environmental incidents year-round, one of which is sudden flash floods. For this reason, all hiking and camping activities within the Havasupai are sometimes cancelled. In 2008, a flood completely overrode the late Navajo Falls, leaving behind two new waterfalls in its stead- the New Navajo and Rock Falls. July and September are the most flash-flood susceptible months of the year.
Visitors are generally given timely warnings before a flooding event and no flood-activity has caused harm to hikers staying at Supai village or the Havasupai campgrounds. However, visitors are still advised to keep these possibilities in mind.