7 more heat

A swath of the United States is facing a dangerous combination of extreme heat and wildfire smoke this week.

More than 85 million Americans across 15 states -- from California to Florida -- are under heat alerts for Wednesday, according to the National Weather Service.

The consecutive days of record-high temperatures combined with high overnight temperatures makes this heat wave especially threatening, as the longer it lasts, the more dangerous it becomes.

Six more heat-related deaths were confirmed in Maricopa County, Arizona, on Wednesday, the Maricopa County Department of Public Health announced. A total of 18 people in Maricopa County, which includes the cities of Phoenix, Mesa and Scottsdale, have died this summer of heat complications, and another 69 deaths are under investigation, health officials said.

A 71-year-old man also died at Death Valley National Park in California on Tuesday as temperatures soared to 121 degrees Fahrenheit, according to the National Park Service. The man collapsed outside the bathroom at Golden Canyon and had likely been hiking the popular trail.

The man was wearing a sun hat and hiking clothes, and carried a backpack when he collapsed, according to the NPS. A helicopter was not able to respond to the scene due to the heat, park officials said. Park rangers performed CPR and used an automated external defibrillator but were not able to revive him.

While a cause of death has not been determined, park officials "suspect heat was a factor," according to the NPS.

A number of cities are shattering records amid scorching temperatures.

Tuesday marked the record-breaking 19th straight day the heat index value was at or above 110 degrees Fahrenheit in Phoenix, Arizona, with no end in sight. Overnight temperatures there also haven't dropped below 90 degrees for a record 9 days in a row.

In Miami, Florida, the heat index value has been at or above 100 degrees for a record 38 consecutive days.

El Paso, Texas, has counted a record 33 straight days with the heat index value at or above 100 degrees.

Las Cruces, New Mexico, has gone a record 17 days in a row with the heat index value at or above 100 degrees.

Tucson, Arizona, broke its all-time record warm low temperature at 86 degrees on Wednesday morning.

The heat wave isn't expected to end anytime soon. The latest forecast shows above-average temperatures for the rest of July, particularly in the West and the South.

The last 16 days on Earth have been the hottest on record and the planet's surface temperature is on track to break a record set only a couple of weeks ago.

Meanwhile, several states in the East are under air quality alerts due to smoke from raging wildfires in neighboring Canada. The smoke was expected to lighten up on Wednesday as the weather front moves through the region.

California is now battling its own wildfires, with heavy smoke drifting over cities such as Fresno and areas up the northern coast. Dangerous smoke was expected to spread into Medford, Oregon, on Thursday.

Severe storms are possible Wednesday night and Thursday across the Plains from the Texas and Oklahoma panhandles up through Minneapolis, with damaging winds, hail and possible brief tornadoes.

Multiple counties in far western Kentucky were under flash flood emergencies on Wednesday afternoon. The area is already experiencing widespread flooding due to significant rainfall Wednesday morning -- up to 10 inches and more in some spots, according to the National Weather Service.

Kentucky Gov. Andy Beshear declared a state of emergency Wednesday afternoon, describing "significant damage" in the town of Mayfield due to heavy rainfall.

"So, the first thing for everyone is be safe and make sure your family is safe," Beshear said in a statement. "Remember, we can replace stuff and we can rebuild homes. We don't want to lose any lives."

Flooding has also been reported across middle Tennessee as the heavy rain moved through on Wednesday – up to 6 inches in some regions. A flood watch will continue in the region today, which includes Nashville.

The influx of rain is being fueled by the abundant heat, moisture and instability in the atmosphere.

Another small area in coastal North Carolina and Virginia, including Virginia Beach and the Outer Banks, could also see severe storms on Wednesday. A tornado watch has been issued in those areas until 7 p.m.

A tornado has been confirmed to strike Halifax County, North Carolina, on Wednesday afternoon. Another tornado, an EF3, struck north of Rocky Mount, North Carolina, according to the National Weather Service's Raleigh office.

The Pfizer facility in Rocky Mount sustained damage, the pharmaceutical company said in a statement. Employees who were in the building were able to evacuate and are "safe and accounted for."

"We are assessing the situation to determine the impact on production," Pfizer said in a statement. "Our thoughts are with our colleagues, our patients, and the community as we rebuild from this weather incident."