Desert Southwest may break all-time heat records

Daniel Casillas, 14, keeps cool at a splash pad Tuesday, June 25, 2013 in Chandler, Ariz. Dangerously hot temperatures are expected across the Arizona deserts throughout the week with a high of 118 by Saturday. (AP Photo/Matt York)

Say it's going to be hot in the Desert Southwest in July and you'll likely get met with a few shrugs. But this weekend and into early next week, it's expected to be hot even by seasoned desert veterans.

A massive ridge of high pressure will be building into the region, bringing the hottest weather in a few years there that has the chance to match or exceed some all-time heat records there.

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.

Las Vegas forecasters are giving an expected high of 117 on Sunday which would tie their all-time record high temperature. Temperatures are expected to push well into the 120s in some of the southeastern California and southern Nevada deserts, with Death Valley forecasted to reach a high of 129.

That is just 5 degrees short of not only their all-time record high but the planet's all-time record high (that at least has been measured). Death Valley has not reached 130 sine the days after that 134-degree record was set in 1913, so this could be a 100-year event if it reaches a degree warmer.

Here is a chart of some of the forecasted highs in the Southwest this week:

It looks like Seattle and Portland will also get some heat from this ridge, but it's uncertain how hot it'll be yet. Forecasts for Seattle are in the mid 80s with Portland into the low 90s for early next week, but if the ridge builds more and is aided by a thermal trough, as some forecast models have suggested, the forecasted temperatures will increase.

The Associated Press contributed to this report.