VIDEO: It may be rainy and cool this weekend, but it's only a matter of time until Arizona's infamous dry heat envelopes the Valley, bringing with it a rise in mountain rescues. Phoenix has more than 41,000 acres of desert parks and mountain preserves and 200 miles of trails that attract more than three million hikers each year. Last year, the city's fire department had to rescue 259 of those hikers — 95 of whom required a helicopter evacuation. While some of those rescues are caused by unexpected health emergencies, the ones that make headlines typically involve hikers running out of water or getting lost because they wandered off trail.