Weather forecasters are predicting record high temperatures across the Phoenix area could cool down by this weekend.
The National Weather Service is showing a low-pressure system will lower the high temperature to 91 degrees by Saturday.
The Weather Service says a high-pressure system is the cause for the heat spell plaguing metropolitan Phoenix this week.
Officials have posted excessive-heat warnings for the lower third of Arizona.
The Weather Service says daytime temperatures in Phoenix are usually in the 90s in May. The high temperature for Tuesday is expected to be 108.
The heat led to an ozone health watch Monday.
People are advised to drink plenty of water and avoid vigorous activity during the hottest part of the day.
This heat wave is more than just uncomfortable -- it's blamed for two deaths.
Authorities say a female tourist from Germany is dead after collapsing during a hike in Tucson's Saguaro National Park West.
The Pima County Sheriff's Department says the 35-year-old woman was hiking with a companion when she collapsed near the Hugh Norris Trail Head just after 2 p.m. Monday.
She was pronounced dead at the scene. The name and hometown of the victim wasn't immediately released.
Sheriff's officials say the woman may have died from heat exhaustion or heat stroke.
The National Weather Service says the high was 105 degrees Monday in Tucson. It was one of the earliest days to reach 105 since the late 1800s.
Over the weekend, a 23-year-old woman died from heat stroke while hiking in Marana, just north of Tucson.
The Associated Press contributed to this report.