Weather in this part of the State is both predictable and completely unpredictable. One thing is for sure, it's hot in the summer. But you may be surprised to hear it also rains, a lot. Flash flooding is common and can be dangerous during the monsoon season of about June through September. 2022 saw heavy rains that closed much of the State Park for a short time and shuttered trails in the National Park. Work is still being done to fix damage. It's no joke. However, the area is generally pleasant and sunny in Spring and Fall, which is why those are the busiest seasons. Winters are usually pretty mild, however it's not unheard of to drop well below freezing at times.
While summer may technically begin in June, the temperatures are well into the 90s by May (and oftentimes by April). Dead of summer temperatures will likely be 100 or higher most of the day. Temperatures will start to cool off a little in September (still hot) and by October we usually see some relief from 90+ temps. In short, expect summer temperatures April through September. You'll hear this a lot, it's a dry heat, meaning there's usually no humidity.
Temperatures are highest along the river and lowest in the mountains, sometimes as much as a 20 degree difference.
The best time to visit is our opinion, November-February. Weather will probably be pleasant and crowds are smaller, with the exception of the busy holidays like Thanksgiving, Christmas and New Years. We still call this season Winter but the temperatures are more sping-like than anything. Weather will likley be pleasant in March as well, but this is the busiest time of year. If you want to come in March, plan ahead and make reservations in the fall.
No matter when you come, bring a hat. It's pretty much a guarantee that the sun will be shining.