Observed changes in annual, winter, and summer temperature in the United States (°F). Changes are the difference between the average for present-day (1986–2016) and the average for the first half of the last century (1901–1960 for the contiguous United States, 1925–1960 for Alaska and Hawai‘i).
Estimates are derived from the nClimDiv dataset (Vose, R. S., S. Applequist, M. Squires, I. Durre, M. J. Menne, C. N. Williams, C. Fenimore, K. Gleason, and D. Arndt, 2014: "Improved Historical Temperature and Precipitation Time Series for U.S. Climate Divisions." Journal of Applied Meteorology and Climatology 53(5), 1232–1251, doi:10.1175/JAMC-D-13-0248.1; Vose, R. S., M. Squires, D. Arndt, I. Durre, C. Fenimore, K. Gleason, M. J. Menne, J. Partain, C. N. Williams Jr., P. A. Bieniek, and R. L. Thoman, 2017: "Deriving historical temperature and precipitation time series for Alaska climate divisions via climatologically aided interpolation." Journal of Service Climatology 10(1), 20). Figure source: NOAA/NCEI.