Wildfires used to die down and even stop at night with cooler temperatures and increased humidity. But a study released Friday says climate change is making burning weather more around the clock in North America because night is becoming warmer and drier. Canadian fire scientists say potential burning hours for fires have increased 36% in the last 50 years. California now has about 550 more fire-friendly hours a year than it did in the 1970s. North American summer nights are warming faster than days, evening relief is evaporating for forests and that means the area of land burned is soaring.