An oppressive heat wave across much of the western United States had cities and their residents sweltering through conditions this weekend that are normally more common at the height of summer.

The blistering heat wave, which has persisted all week throughout California and the desert Southwest, will continue to build and spread east into the central U.S. in the coming days. Temperatures that are 20 to 40 degrees Fahrenheit above average for this time of year will be common from the Southwest into the Great Plains, according to the National Weather Service.

More than 150 daily temperature records and around 50 monthly all-time records have already been shattered since Tuesday, the weather service said, with more expected to fall this weekend and in the coming days.

Parts of California were well above seasonal averages heading into the weekend, with Death Valley reaching a blistering 105 degrees on Thursday, a new monthly record. Highs are expected to remain well into the triple digits there into next week, according to the National Weather Service.

Southern Nevada was similarly grappling with summerlike conditions this weekend. Las Vegas hit 96 degrees on Saturday and is forecast to reach 93 degrees on Sunday. More than 40 daytime cooling stations were opened throughout the city to help people cope with the heat.

“While Southern Nevada is no stranger to extreme heat, we are facing an unprecedented heat wave months ahead of the summer season,” Clark County Commissioner Marilyn Kirkpatrick said Wednesday in a statement. “Our bodies are not yet acclimated to these temperatures, and that puts people at greater risk for heat related illnesses.”

The Las Vegas office of the National Weather Service urged people to take proper precautions to avoid heat-related illness.

“If you’re spending time outdoors, remember to wear sunscreen, eat light meals, and avoid caffeine & alcohol,” the weather service said on X.

In Colorado, Fort Collins reached an astounding 91 degrees on Saturday, a new all-time high for March since the city’s recordkeeping began in 1893. The 91-degree milestone also surpassed April’s hottest recorded temperature in Fort Collins by 2 degrees, according to the National Weather Service.

“The city hadn’t recorded a March high above 81F prior to 2026,” the Boulder office of the NWS said Sunday on X.

Denver, meanwhile, hit 86 degrees on Saturday, also setting a new record for the month of March. The heat, low humidity and breezy winds in Colorado are raising the risk of wildfires across the state.

This week’s historic heat wave was caused by a heat dome, a stubborn ridge of high pressure that has trapped hot air over a huge swath of the western U.S. like a lid on a pot.

It can be challenging to tease out the exact influence of climate change on specific extreme weather events, but global warming is known to make heat waves more frequent, more intense and longer-lasting.

A new report from the World Weather Attribution group, which analyzes the influence of climate change on extreme events, said Friday that this March heat wave “would have been virtually impossible without human-induced climate change.”

In Phoenix, where temperatures reached 105 degrees on Friday and Saturday — record highs for the entire month of March — several popular hiking trails have been closed during daytime hours. The closures occurred months earlier than these types of heat protection measures normally go into effect.

The Phoenix Trail Heat Safety Program, which was established in 2021, restricts access to trails in and around the city when the National Weather Service’s extreme heat warnings are in effect. This weekend, trails at Camelback Mountain Preserve, Phoenix Mountains Preserve and South Mountain Park and Preserve will be restricted from 8 a.m. to 5 p.m. local time.

An extreme heat warning remains in effect in the region through Sunday. The Maricopa County Department of Public Health, which includes Phoenix, told people to stay indoors with air conditioning as much as possible in the coming days.

“Remember to drink your water, limit outdoor activities during peak heat, and check in on loved ones who are at risk,” public health officials wrote in a post on Facebook.

A number of outdoor events in the Phoenix area have had to make adjustments because of the extreme heat. At least 10 Major League Baseball spring training games, for instance, have moved their start times from the afternoon to after 6 p.m. local time in order to escape the worst of the triple-digit temperatures, the Cactus League said in a statement.

In Glendale, Arizona, the local fire department said it transported approximately 30 people to area hospitals on Saturday for heat-related illnesses during the Luke Days Air Show.

“In addition to those transports, Glendale Fire Department personnel, along with our public safety partners, evaluated and treated a number of other attendees on scene who were experiencing heat-related symptoms,” a spokesperson for the fire department told NBC News in an email.

The National Weather Service said temperatures on Sunday are expected to be in the 90s and 100s across the Southwest and in the 80s in parts of Utah, Idaho, Wyoming, Colorado and New Mexico. Across the Great Plains, meanwhile, highs will range from the 70s into the 90s.