June 15th is the traditional beginning of the monsoon (seasonal rain) season in many areas of the southwest. In some places the summer monsoon will provide over half of the total annual precipitation.
The sudden and intense rain can strand unsuspecting boondockers:
- low areas may become impassable
- dirt roads NF and BLM lands can become extremely slick and rutted, or wash out one or both tracks
- vehicles that have been camping for many days can sink in the softened soil and be unable to drive out (don't ask me how I know this)
I encourage folks camping in the SW to pay attention to any ruts, dips, or evidence of previous water events. Carry extra shelf stable foods like beans, grains, etc in case you need to wait for the sun to dry up the roadway out of camp.
BN: water storage isn't critical because by definition it's falling from the sky and can be caught with little effort. On one memorable/traumatic afternoon in Flagstaff last year I caught 20 gallons of water off a tarp in an hour.