This weekend's scorching weather around the world

Excessive heat warnings remained in effect on Sunday for people around the world, from the United States, to Europe, and Japan.

The heat wave that's spreading across a swath of the U.S. from Oregon, down the West Coast, and into the Southwest including Texas through Alabama, is unusual, said Zack Taylor, a meteorologist with the National Weather Service's Weather Prediction Center in College Park, Md.

There's a mass of high pressure air sitting like a dome "parked" over the affected areas and it's deflecting any rain and storm systems that could provide relief to more than 100 million Americans under heat warnings and cautions, said Taylor.

Phoenix, Ariz., is centred squarely under the heat dome, and the temperature was expected to climb to 47 C on Sunday, matching the high on Saturday, according to the National Weather Service.

Temperatures in Arizona's capital have been at or above 43 C every day for 16 consecutive days, nearing the 1974 record of 18 days in a row for that level of heat.

Some of the estimated 200 cooling centres in metro Phoenix planned to extend their weekend hours, and emergency rooms were ready to treat people with heat-related illnesses.

In Nevada, an intense heat wave threatens to break Las Vegas's all-time record high of 47.2 C this weekend. Misters have been set up along the Las Vegas Strip to provide some relief.

The National Weather Service says the extreme heat will continue through the middle of this week. Forecasters have warned people to take precautions to protect themselves from the heat, such as cancelling outdoor activities during the day.

High temperatures that have already sparked wildfires in Spain and Croatia were also being felt in central parts of Europe, including Germany, Poland and the Czech Republic — and with another heat wave in the forecast, more high temperatures were expected across the continent in the coming days.

On Spain's La Palma Canary Island, officials ordered more than 4,000 people to evacuate their homes on Saturday because of a raging wildfire.

The fire, which has destroyed at least 20 homes, coincides with a heat wave that has persisted for nearly a week in southern and central Europe.

Italy issued hot weather red alerts for 16 cities on Sunday, with meteorologists warning that temperatures will hit record highs across southern Europe in the coming days.

Forecasters say a new weather system with extreme heat pushed into southern Europe from North Africa on Sunday and could lift temperatures above 45 C in parts of Italy early this week. "We need to prepare for a severe heat storm that, day after day, will blanket the whole country," Italian weather news service Meteo reported on Sunday.

"In some places ancient heat records will be broken."