The hot, humid conditions in Washington, DC, on Thursday made for electricity. Air temperatures topped 94 degrees Fahrenheit (34 degrees Celsius) – or 5 F (3 C) higher than the 30-year normal high temperature for Aug. 4, according to the National Weather Service. More heat can draw more moisture into the atmosphere, and it also encourages rapid updrafts – two key factors for charged particles, which lead to lightning. A key study published in 2014 in the journal Science warned that the number of lightning strikes could increase by 50% this century in the United States, with every 1 C (1.8 F) of warming translating into a 12% increase in the number of lightning bolts. Sign up now for FREE unlimited access to Reuters.com Register Rapidly warming Alaska has seen a 17% increase in lightning activity since the cooler 1980s. And in typically dry California, a siege of about 14,000 lightning strikes in August 2020 sparked some of the state’s largest wildfires on record. Beyond the United States, there are signs that lightning is also shooting in India and Brazil. But even as lightning strikes increase, getting struck by one is still extremely rare in the United States, experts say. About 40 million lightning strikes hit the country each year, according to the Centers for Disease Control — with the odds of being struck less than 1 in a million. Lightning strikes a tree in Lafayette Park across from the White House, killing two people and injuring two below, during an evening thunderstorm on Aug. 4, as seen in this frame from a Reuters TV video camera mounted on a nearby rooftop in Washington, U.S. August 4, 2022. REUTERS/REUTERS TV read more Among those hit, about 90 percent survive the ordeal, the CDC says. The country counted 444 lightning deaths from 2006 to 2021. The two men and two women struck by lightning Thursday while visiting Washington’s Lafayette Square, north of the White House, were among the unlucky few — struck by a bolt that struck the ground during a violent afternoon thunderstorm . The lightning struck near a tree standing meters away from the fence that surrounds the presidential residence and offices across from the square, which is often filled with visitors, especially in the summer months. All four victims suffered serious, life-threatening injuries and were transported to area hospitals. Read More Two of them later died: James Mueller, 76, and Donna Mueller, 75, of Janesville, Wisconsin, the Metropolitan Police Department said. “We are sorry for the tragic loss of life,” the White House said in a statement Friday. “Our hearts go out to the families who lost loved ones and we pray for those who are still fighting for their lives.” A third victim, a 29-year-old man, was pronounced dead later Friday, the Metropolitan Police Department said. Further details about the victim were being withheld pending notification of next of kin. Because heat and humidity are often required to produce lightning, most strikes occur in the summer. In the United States, the populous, subtropical state of Florida sees the most people killed by lightning. Sign up now for FREE unlimited access to Reuters.com Register Reporting by Gloria Dickie in London. Additional reporting by Frank McGurty in New York and Chris Gallagher in Washington. Edited by Louise Heavens, Mark Porter & Shri Navaratnam Our Standards: The Thomson Reuters Trust Principles.