Thousands of firefighters battling a wildfire in Northern California received some help from the weather hours after it exploded in size, scorching an area greater than the size of Los Angeles. The blaze was one of several tearing through the western United States and Canada, fueled by wind and heat. Cooler temperatures and an increase in humidity could help slow the Park Fire, the largest this year in California. Its intensity and dramatic spread led fire officials to make unwelcome comparisons to the monstrous Camp Fire, which burned out of control in nearby Paradise in 2018, killing 85 people and torching 11,000 homes.