The "heat dome" has some Americans longing for the spine-shivering days of the polar vortex.
On Saturday, the dome — a ridge of high pressure that traps hot air for an extended period of time — had 110 million Americans under heat advisories, warnings or watches after many had already suffered through two days of the sweltering conditions.
Washington was the only state of the lower 48 on Friday spared from having some portion hit by at least 90 degree temperatures.
But it's the heat index — the "feels like" temperature when heat is paired with humidity — that created health risks on Friday and continued to be a threat through the weekend.
Heat indices were expected to linger between 100 and 110 degrees across the country on Saturday and Sunday, according to Weather.com.
According to the National Oceanic and Atmospheric Administration (NOAA), the widespread heat wave is especially dangerous because lows at night will hardly dip below 80, depriving Americans from relief from the "oppressive" heat.
Excessive heat has killed more Americans in the past decade — an average of more than 100 people per year — than any other weather event, according to the National Weather Service, which recommends staying hydrated and limiting outdoor activities.
While the current heat wave hasn't been attributed to global warming, climate scientist Dan Collins told The Associated Press that it has been a factor in many recent extended periods of high heat.
And there have been more hot days than usual. June marked 14 consecutive months of record heat around the world, according to NOAA