The only saving grace is a summer monsoon over Arizona, which brings moisture and some cooler temperatures, Hoxsie said. According to the weather service, the dome is created when air sinks below a slow-moving high pressure system and caps the atmosphere. Now, that dome of high pressure is blanketing the Southland. “That dome has been stretching and broadening and has reached over our area,” said meteorologist Kathy Hoxsie of the National Weather Service in Oxnard. The scorching heat prompted county public health officials to issue a heat alert for Los Angeles, the valleys and desert.

Source: Los Angeles Times July 21, 2016 22:02 UTC