Last updated September 29, 2021

Increasing frequency, intensity and duration of observed global heatwaves and warm spells

  • Uses the latest HadGHCND daily temperature dataset, global trends in observed summertime heatwaves
  • Calculates and analyzes annual warm spells for 1950–2011
  • Studies three indices that separately focus on maximum temperature (TX90pct), minimum temperature (TN90pct) and average temperature (EHF) with respect to five characteristics of event intensity, frequency and duration
  • Finds increases in heatwave/warm spell intensity, frequency and duration despite which index is employed
  • Finds that TX90pct and TN90pct trends are larger and exhibit more significance for warm spells, implying that non-summer events are driving annual trends over some regions
  • Finds arger increases in TN90pct aspects relative to EHF and TX90pct are also observed