100 million under heat warnings in Plains

While the heat in Europe is garnering the most headlines, a potent heat wave is hitting the U.S. as well. The heat stretches from the Canadian border to the U.S. border with Mexico, with 100 million under heat warnings and advisories.

Driving the news: Heat warnings on Tuesday cover the entire state of Oklahoma and the vast majority of Texas, where the electrical grid will once again be tested.

• High temperatures in Oklahoma City are forecast to reach 112°F on Tuesday, which is about 14°F above average for this time of year.

Why it matters: Extreme heat can be deadly and imposes costs on the economy by making outdoor work on farms and construction sites more difficult to impossible. It poses the greatest health risks to the elderly, those with preexisting illnesses and anyone without access to cooling.

• It also raises electricity demand, leading to possible rolling power outages in order to keep the power grid stable in some areas.
• Studies show that human-caused climate change is making heat waves more likely to occur, more severe as well as longer-lasting.

The big picture: A sprawling area of high pressure, or heat dome, is in place across the Plains, with numerous record high temperatures forecast from Texas to Nebraska and in other states as well, according to the National Weather Service.

• The drought across Texas, parts of the Plains and much of the West is only making it hotter, which is in turn worsening the drought as part of a positive climate feedback loop.
• According to the National Weather Service, this will be one of the hottest weeks of the year for many Americans. "Dangerous heat will continue to impact a large portion of the U.S. this week, with now more than 100 million people under excessive warnings or heat advisories," the NWS stated on its website.

• "This includes most [of] the southern Plains and lower Mississippi Valley, as well as parts of the central Plains and the lower Missouri Valley."
• The heat is expected to branch out into the Mid-Atlantic and Northeast starting on Wednesday.

What's next: Over the longer term, computer models have been projecting above-average temperatures along with dry conditions across the Plains to the West Coast, which is a recipe for an increasing number of wildfires, along with intensifying drought.