What is a heat dome, and why is it causing dangerously high temperatures in Western U.S. states?

A heat dome is causing heat waves and extreme temperatures to linger in the Western part of the country.

FILE - The unofficial temperature hits 108 degrees at dusk at Sky Harbor International Airport in Phoenix on July 12, 2023. Parts of California, Nevada and Arizona are expected to bake this week as the first heat wave of the season arrives with triple-digit temperatures forecast for areas including Phoenix, which last summer saw a record 31 straight days of at least 110 degrees Fahrenheit (43.3 Celsius). (AP Photo/Matt York, File)
Triple-digit temperatures are expected to stay in the western part of the country due to a heat dome. (Matt York/AP Photo)

The hottest months of the year are fast approaching and thanks to a heat dome set to engulf the Western part of the country in the coming days, dangerously high temperatures are on the forecast for many Americans.

☀️ What is a heat dome?

A heat dome happens when hot ocean air gets trapped over a certain area due to high atmospheric pressure.

Heat domes and heat waves often happen at the same time, with domes keeping the raised temperatures around longer.

🌎 Where did it come from?

According to USA Today, the current heat dome affecting the United States is partly related to a similar phenomenon that has been taking place over Mexico recently. Mexico is experiencing its worst drought in over a decade and has suffered through crop shortages over the last month.

Other recent severe weather in the United States may also be linked to the heat wave from Mexico. Storms typically form on the periphery of heat domes, and over the last few weeks, the U.S. has experienced massive rainfall and flooding in Southern states and the most tornadoes nationwide since 2011.

🌤️ Who will be affected by the heat dome?

The Western part of the United States is expected to experience the worst of the heat dome. Las Vegas is preparing for “life-threatening,” triple-digit temperatures this week, as well as part of Arizona. Death Valley, Calif. — which is nearly 260 miles from Los Angeles — is projected to see temperatures in the 120s.

The National Weather Service has already issued several excessive heat advisories across California and the rest of the West on different days over the last week. Those advisories aren’t scheduled to be lifted until Thursday or Friday.

California has already experienced effects from the high heat, with several wildfires starting over the past few days. In Tracy, Calif. — about an hour outside of San Francisco — a 14,000-acre fire was fueled by wind and the high temperatures. Although the fire is now 75% contained, the high temperatures in the coming days can still pose challenges for those trying to put out the remaining fires.

🥵 Potential heat-related health issues

According to the National Integrated Heat Health Information System, children and older adults are the most susceptible to heat-related illness, including heat exhaustion, heat stroke and heat rash. The U.S. Center for Disease Control and Prevention provides recommendations on its website for how to identify and treat these and other heat-related illnesses.