Map of U.S. climate divisions showing the change in the average number of annual fire weather days — days that have low relative humidity, high heat and strong winds — from 1973 to 2024. The southwestern U.S. saw the greatest increase in fire weather days, with parts of California, New Mexico and Texas seeing an increase of more than 60 days per year. Parts of South Dakota, North Dakota and Louisiana saw the greatest decrease, with more than 10 fewer fire days in 2024 compared to 1973.