Western US Braces for Record March Heat Wave

A powerful heat wave is building across the western United States, bringing unusually high temperatures to millions from California to Texas and as far north as Montana, with the event underway this week and expected to persist through later next week.

The National Weather Service has issued extreme heat warnings and alerts for areas including San Francisco and Phoenix, with more likely to follow as the heat intensifies. Forecasts indicate temperatures up to 30 degrees above average for March, potentially shattering dozens of daily and monthly records across the West and parts of the Plains states. In Phoenix, temperatures are projected to reach at least 106 degrees Fahrenheit, surpassing the city's all-time March high of 100 degrees and staying above 100 degrees for several days. Many locations could also record their earliest 100-degree readings on file and all-time March highs.

Meteorologists attribute the event to a record-strong heat dome, a broad high-pressure system that extends thousands of feet into the atmosphere. This system compresses air below it, raising temperatures while suppressing storms and diverting weather patterns around it. Experts note that this heat...