Capturing the pace of extreme diurnal temperature change in climate-health assessment

: Climate-health surveillance has made major progress in quantifying heat, cold, and diurnal temperature range (DTR), yet the speed of temperature change remains under-specified in many exposure assessments. We propose extreme diurnal temperature change (EDTC) as a rate-sensitive descriptor of rapid within-day thermal transitions. EDTC should not be treated as a validated universal threshold or as a substitute for DTR. Instead, it offers a complementary way to ask when the same thermal range is delivered over a shorter period, when abrupt cooling or warming occurs, and which populations or places lack the buffering capacity to reduce exposure.