This dataset consists of four different sub-datasets: degree days below 65°F (or "heating degree days"), degree days below 0°F, degree days below 32°F (or "freezing index"), and degree days above 32°F (or "thawing index"). All were derived from the same dataset of outputs from dynamically downscaling one reanalysis (ERA-Interim) and two CMIP5 GCMs (GFDL-CM3, NCAR-CCSM4) over Alaska using the Weather Research and Forecasting model (WRF). Data from the GCMs are driven exclusively by the RCP 8.5 emissions scenario. Heating degree days, degree days below 0°F, and freezing index were computed in the following way: subtract the daily mean temperature values from the threshold value and compute the sum of this time series for the given calendar year. Thawing index is instead computed as the annual sum of the quantities resulting from subtracting the threshold (32°F) from the daily mean temperature values.