2025 USGS Benchmark Glaciers Ablation Season Positive Degree Days

Cumulative 2025 ablation season positive degree days (sum of daily mean temperatures >0°C, when the glacier is melting), May 1–Oct. 30^th, at each USGS Benchmark glacier’s median elevation based on local weather station data (O'Neel et al., 2019; https://doi.org/10.5066/F7HD7SRF). The bold black line shows the 1991–2020 median, with dark gray shading indicating the interquartile range and light gray shading the total historical range for the reference period. Red shading indicates periods where 2025 accumulation exceeded the 1991–2020 median; blue shading indicates periods where it fell below. Boxplots at right summarize the full period-of-record distribution of seasonal PDD totals for each glacier, with the box spanning the interquartile range, the internal line marking the median, whiskers extending to the total range, and the colored dot indicating the 2025 seasonal value. Rank and percentile are reported relative to each glacier's individual period of record. Ablation season ranks are reported from lowest (coolest) to highest (warmest).