A historic heat wave is affecting the West, breaking all-time, monthly and daily records and putting the California electricity grid to test. The heat is relentless, potentially peaking Tuesday but sticking around straight through the upcoming weekend.
The big picture: The immediate cause of the heat wave is an unusually strong area of high pressure, or heat dome, that is parked over the western U.S., causing air to sink and dry out, stifling any widespread rainfall.
