It's been a long, hot summer across much of the Northern Hemisphere, and the United States is no exception. As global climate change sends mid-year temperatures climbing higher and higher, experts are concerned that deaths from extreme heat may soon become a regular occurrence, even in the world's most developed countries. CGTN's Phil Lavelle has the story.

From coast to coast, the U.S is seeing more heatwaves. And those heat waves are killing more people.

JASON SAMENOW, WEATHER EDITOR, WASHINGTON POST "We've had this enormous heat dome over the western two-thirds of the U.S for much of the summer."

The Centers for Disease Control and Prevention saying extreme heat, now causing more deaths in U.S. cities than ALL other weather events combined. Early July saw dozens of people die across North America. 34 dead in Montreal alone - after several days of record-high temperatures in Canada. The southwest United States, too, struck by a heat wave in July. At one point, a heat-dome held temperatures above 32 degrees Celsius in 44 of the 50 U.S. states.

JASON SAMENOW, WEATHER EDITOR WASHINGTON POST "Yeah, so it's an enormous area of high pressure at high altitudes. The air sinks under the heat dome, it compresses and it heats up the air and we've seen that not only in the eastern and western areas of the United States but in many areas of the world this summer."

PHIL LAVELLE WASHINGTON DC "Here in Washington DC, the average temperature this time of year, 30 degrees Celsius. Right now, it's 32 Still hot, still humid, still uncomfortable. It's way better than many other parts of the country."

California's really feeling the effects right now. Wildfires are common. But the extreme dryness, increased heat and warm winds. A literal tinderbox.

JASON SAMENOW, WEATHER EDITOR WASHINGTON POST "We've seen these heat domes getting hotter and hotter over time. We've seen the increasing number of all-time record highs set not only in the United States, but all over the northern hemisphere this summer, so as the world continues to warm, we should expect these heat domes to become more intense and yes, this will be the new normal."

And much of the world IS sweltering from Asia to Europe, records are breaking.

JASON SAMENOW, WEATHER EDITOR WASHINGTON POST "And it's not just the multiple days of hot weather - seemingly endless - but the nighttime too, especially in the big urban areas where the temperatures don't go down much even when the sun has. As always, the older, the vulnerable, most in danger. And the worst bit - summer's not over yet. There are still several weeks left of it to run. Phil Lavelle, CGTN, Washington."