The temperature in Phoenix is expected to climb through Saturday, when forecasters say the heat could set a new record. The record high for the same date in June is 117 degrees set in 1994, said meteorologist Mark O'Malley of the National Weather Service in Phoenix. The forecast for this coming Saturday currently is for 118 degrees.
"We'll certainly be challenging records this week," O'Malley said Tuesday.
The heat wave comes with a strong high-pressure system expected to build over the entire western U.S. and which will be centered over northern Arizona at its peak on Friday, the weather service says.
O'Malley said temperatures will soar through the week across Arizona, New Mexico, California, Nevada, Utah and into parts of Wyoming and Idaho, where forecasters are calling for triple-digit heat in the Boise area through the weekend.
"It's going to cover a large portion of the western United States," he said.
Officials say extra personnel have been added to the Border Patrol's Search, Trauma, and Rescue unit to assist with increasing numbers of rescues throughout the summer months as migrants crossing rugged terrain succumb to heat, exhaustion and dehydration.
"June is the deadliest month for migrants in Arizona. It is consistently the month where most migrants die here," said Border Patrol spokesman Andy Adame. "Absolutely it's a crime to enter the United States illegally, but the penalty for that crime shouldn't be death."
O'Malley said the weather system won't help with wildfires—either ones already burning or new ones that might pop up.
"Given we're going to have low humidity and extremely hot temperatures, and everything is already dry out there, for any fire that is ongoing or new ones that start, this could be very problematic," he said.
Temperatures in mountainous northern Arizona also are expected to approach all-time highs. The forecast in Sedona calls for the temperature to hit just one degree under the June 1990 and July 1995 records of 110 degrees.
Associated Press writer Felicia Fonseca contributed to this report from Flagstaff.