Wildfires west of Athens jumped containment lines, a day after a midair collision between two helicopters killed two crew members. In France, firefighters in the region around Bordeaux guarded against potential flare-ups inside a still-burning scar four times the size of Paris. The dry spell was accompanied by sweltering temperatures across much of the U.K., following heat waves in May and June. Rising temperatures and prolonged drought leave vegetation drier and more combustible, allowing fires to spread faster and burn more intensely. The wildfire burned about 420 square kilometers (162 square miles), making it France’s largest wildfire on record.