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 2022. The southwestern U.S. saw the greatest increase in fire weather days, with parts of California and New Mexico seeing an increase of more than 55 days per year. Parts of South Dakota, North Dakota and Louisiana saw the greatest decrease, with more than 10 fewer fire days in 2022 compared to 1973.