Indeed, the prediction is for temperatures to range as high as 130 degrees in California’s Death Valley – which would be the highest there since 1913. Bullhead City, Ariz.; Blythe, Calif.; and Palm Springs, Calif., are all forecast to approach or reach the low 120s. Phoenix is expected to max out in the middle to upper 110s, and Las Vegas could top out at 117 degrees. When it gets that hot, nighttime temperatures remain in the 90s.
Even parts of the typically cooler Pacific Northwest could be baking over the next several days, according to the Weather Channel: Portland, Ore., and Seattle in the 90s, and Boise, Idaho, in the low 100s and perhaps as high as 108 by Tuesday.
Meanwhile, the National Interagency Fire Center in Boise is forecasting “above normal potential for significant fire activity in the West Coast states, the Southwest, and portions of Idaho and Montana.”
Causing the heat wave, according to the National Weather Service, is a "massive and unusually strong high-pressure system" over the region, resulting in “dangerously hot temperatures.”