An unusually strong area of high pressure — or heat dome — is leading to historic extremes of heat in the Southwest.

Dozens of cities and towns in the Southwest United States set record highs on Sunday — some nearing their hottest days ever recorded.

Today, the heat wave reaches its peak, and more records are set to fall.

Locations that established daily record highs Sunday included: Yuma (120), Phoenix (118),  Tucson (115), Burbank, Calif. (109), Albuquerque (103, tie), and Santa Fe (102).

Several of these temperatures ranked among the hottest ever recorded in their respective locations:

The scorching heat is being blamed for the deaths of four hikers in Arizona, in separate incidents.

Temperatures on Monday are forecast to be just as hot, if not hotter, across the region.

Excessive heat warnings blanket much of Southern California, southern Nevada, and southern Arizona.

Phoenix’s temperature is again forecast to soar to between 115 and 120 degrees, meaning it could rank among its hottest five days on record. Las Vegas, after hitting 110 degrees on Sunday, may hit 114 degrees or so, which would be a record for the date.

In Southern California, the National Weather Service in Los Angeles is describing the heat wave as “dangerous” and “deadly,” forecasting temperatures five degrees higher Monday than Sunday.

Forecast highs away from the beaches are expected to soar into the 90s and 100s — downtown Los Angeles had already hit 98 degrees at 10 a.m. local time:

Hotter-than-normal weather is expected to linger over the Southwest through the week, although its intensity is forecast to drop a notch starting Wednesday.