Desert Southwest may break all-time heat records

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:

City Friday Saturday Sunday Monday Phoenix, AZ 118 117 116 113 Las Vegas, NV 114 116 117 115 Laughlin, NV 121 122 123 122 Lake Havasu City, AZ 120 121 124 117 Kingman, AZ 110 110 112 108 Death Valley, CA 126 128 129 129 Barstow, CA 114 118 117 116 Needles, CA 122 123 124 120 St. George, UT 113 113 114 112 Yuma, AZ 118 116 113 112 Tucson, AZ 112 112 111 109 Reno, NV 101 101 103 104 Boise, ID 101 102 105 104 Ontario, OR 101 103 105 105 Tri-Cities, WA 95 98 100 103 (105 Tue) Walla Walla, WA 94 96 97 101 (102 Tue) Pendleton, OR 94 96 98 102 (103 Tue) Salt Lake City, UT 103 104 103 102

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.