A heat wave hovering in the central and southern states is expanding north to states not accustomed to intense and prolonged heat.
"This is going to be especially bad in the upper Midwest," said Chris Vaccaro, a spokesman for the National Weather Service.
Temperatures will be in the 90s and possibly hit 100 degrees in some places. When humidity is factored in, the heat index could reach 115 degrees.
These soaring mercury levels are unusual for states like North and South Dakota, Minnesota and Wisconsin, Vaccaro said, which makes this heat wave particularly dangerous in those places. In Minneapolis alone highs could reach 15 degrees above normal.
As the heat wave expands to the north, the Minnesota Twins begin the first of a series of home games at Target Field in Minneapolis Friday night.
"We'll be ready for each and every day it's hot," said Kevin Smith, spokesman for the baseball team.
If it gets hot enough, water stations will be available by the gates and on various levels of the ballpark.
"It's all about staying hydrated," said Smith, who added first aid teams will be on hand to monitor fans if temperatures hit extremes.
The city of Minneapolis warned residents to take precautions in the heat by drinking more fluids, staying indoors, wearing light-colored, loose-fitting clothing and never leaving a person or animal in a closed, parked car.
In Kansas City, Mo., temperatures were in the 90s on Friday, but with the humidity it felt like 100 degrees or more in most areas, according to the weather service. And there was no relief in sight. High heat and humidity were forecast for Kansas City until next Friday.
Cooling centers in the area were opened, and 59-year-old Ronald Vincent Artis was taking advantage of the air conditioning at one center.
"It's very important," said Artis. "I've got high blood pressure. I get dizzy and I get migraines."
Artis said he was homeless and typically did not spend the night in shelters. But last night, for the first time since April, the heat forced him to seek refuge indoors.
Nine suspected heat-related deaths have been reported in Kansas City this summer, including three this week, according to the Kansas City Health Department.
"People really do need to take heed and whenever they can be in an air-conditioned environment," said Bill Snook, department spokesman.
"Electric fans are good only up to a point."
In South Memphis, Tenn., the heat was apparently to blame for the death of a 72-year-old man. The man died Wednesday, according to the Shelby County Health Department.
The air conditioning in his home was malfunctioning and blowing hot air. And while a fan was in use, the windows were closed, the agency reported.
This is the third apparent heat-related death in West Tennessee this summer. Two people died in June.
The excessive heat continued to aggravate drought conditions in the southern part of the county.
Fourteen percent of the continental United States, mostly in Texas, Louisiana and New Mexico, have had the driest first six months of the year on record since 1895, according to weather service meteorologist Victor Murphy, based in Fort Worth, Texas.
"It's a double edge sword," said Murphy. "There's no moisture in the soil to absorb the heat of the sun."
He said that leads to prolonged heat, prolonged drought and less chance of rainfall.
On Friday 12 states were under heat advisories, warnings or watches from Texas north to Minnesota, and the heat wave is expected to move east by the middle of next week.
"It's going to be pretty significant," said Vaccaro. "It's going to expand and worsen throughout the weekend."
So far in July, 882 high temperature records in the United States have been tied or broken, according to the weather service.
Extreme drought
In the thick of the heat wave is Oklahoma where Gov. Mary Fallin asked Oklahomans to pray for rain this Sunday.
"The power of prayer is a wonderful thing, and I would ask every Oklahoman to look to a greater power this weekend and ask for rain," Fallin said in a news release on Thursday.
Fallin on Thursday also issued a ban on outdoor burning for the western half of the state because of the extreme drought conditions.
"The number of wildfires we have had over the last few months is extremely tough on our state firefighters," Fallin said.
Earlier this year Texas Gov. Rick Perry asked Texans to pray for rain because of the drought there.
As of July 12, about 72 percent of Texas and 43 percent of Oklahoma are experiencing the worst possible drought conditions, according to the U.S. Drought Monitor.
On Thursday, 10 states were under heat advisories or watches, down from earlier in the week when 24 states were on the list.