Daytime temperatures can fluctuate quite a bit regardless of the season/month and although we have listed average temperatures and descriptions below, mother nature is unpredictable. Monsoon season weather (mid-July-August) for example, can see 10-20 degree shifts in temperature within a short period of time so having proper clothing and rain gear is very important. Temperatures are cooler in the east in (Lees Ferry – river mile 0) and warm as you travel west (Lake Mead – river mile 280). Those who are hiking the bright angel trail, keep in mind that the temperature at the top of the south rim is usually about 20 degrees cooler than at the bottom.
April: Temperatures during the day between 70-85 degrees and temperatures at night can be in the 50’s. Ideal daytime temperatures for extended hikes however can be chilly early morning especially if rafting through a rapid first thing. Long-sleeve/underwear, proper rain gear, fleece and warm socks is a must for trips in April.
May: Daytime temperatures can vary between 80-95 degrees, and very comfortable sleeping temperatures between mid 50’s to mid 60’s. Again, a rapid first thing in the morning before the sun rises past the canyon walls, or cloudy periods after a rapid can make things rather chilly. Long-sleeve/underwear, proper rain gear, fleece and warm socks is recommended.
June: Temperatures begin rising and you can expect 90’s to over 100 degrees. Humidity is low and this helps, but June offers the least amount of cloud coverage so this can ‘feel’ as the hottest month even if the temperatures aren’t as high as July and August. Sleeping temperatures can be between 70-80 degrees.
July: Daytime temperatures over 100 degrees, and nighttime temperatures between 75-80 degrees. By mid-July expect more cloud coverage and is the beginning of monsoon season where you can anticipate late afternoon thunderstorms (usually do not last very long) and clear skies by nightfall. The clouds and rainfall can offer relief from the high temperatures.
August: Temperatures still in the 100’s during the day and you can still expect some relief and cooler temperatures from late afternoon thunderstorms. Monsoon season begins tailing off towards the end of August however you can still anticipate hot temperatures throughout. Sleeping temperatures between 70-80 degrees.
September: Things begin cooling down again with temperatures in the mid-90’s during the day and 65-70 degrees at night. Occasional late season monsoon weather can call for some late afternoon thunderstorms early in September, but are rare.
October: Temperatures continue to cool as you can expect temperatures similar to April, with sleeping temperatures between 50-60 and daytime in the mid 80’s making for ideal hiking conditions. Expect cool mornings and be prepared with long-sleeve/underwear, proper rain gear, fleece and warm socks.