When looking at the numbers, Arizona temperatures may seem higher than where you are coming from, but remember it really is a dry heat. The humidity is usually less than 20 percent. Also, the towering canyon walls provide shade in the afternoon and most mornings and you realize why Grand Canyon is a very comfortable camping environment. With our lack of flying bugs and mosquitoes due to the dry environment, it allows for sleeping out under the stars most river nights.
April and early May always have the possibility of a late winter storm so we recommend a few more items of warm clothing. Late May through early July are mainly sun, sun, sun with little chance of rain. Mid-July to early September is usually sunny in the mornings, with a chance of an isolated afternoon thunderstorm to cool things off. If you are lucky enough to experience a canyon storm, you will thrill at the sound of the echoing thunder and the sight of waterfalls cascading off the canyon rims. We seldom get full overcast rainy days at any time of year. Where you set up camp at night has an effect on the night temperature. Near the river is cooler than closer to the canyon walls which give off heat collected during the day. Truthfully, the weather is seldom an issue with our guests.
The water in the Grand Canyon is released from Glen Canyon Dam on Lake Powell, 15 miles above our Lee’s Ferry launch point. The dam provides us with two beneficial things:
Cold Water – Water is released from the dam at about 50 degrees, even in mid-summer, and warms to around 65 degrees as it approaches Lake Mead. Since the water is moving through the Canyon in a short amount of time, this varies very little with the season. Though we sometimes wish the water was a little warmer, the cold water provides a beach-like cooling effect near the river. It helps make even the hottest days comfortable while on the rafts.
Consistent Flows – There is no seasonal snow melt flow as the water release is very similar throughout the rafting season. There are small daily fluctuations from the change in release due to power needs, but we seldom worry about the water releases. Current laws require for a yearly allocation of water to be released for the downstream states and this provides us good rafting water even in a drought year. The water color can change when there is a thunderstorm in the area, but that just returns the river to its original red-brown color for a period of time. It really has no effect on the rafting.