<p>Global warming is increasing the number and intensity of many extreme weather and climate events. Here we argue that extreme day-to-day temperature changes, exceeding the 90th percentile threshold of historical records, are an independent, but largely ignored, aspect of extreme weather events. Such extreme temperature changes have a stronger impact on human health in many locations than do diurnal temperature variations. Global observations show that such events have become more frequent since the 1960s in low and mid-latitudes but decreased at high latitudes, primarily due to GHG forcing. Climate models project a further amplification of extreme day-to-day temperature changes under warming, with frequency, amplitude and total intensity rising by ~17%, ~3% and ~20%, respectively, by 2100 in regions covering 80% of global population. Increased extreme day-to-day temperature changes are associated with drier soil and increased variability in pressure and soil moisture, posing substantial risks to societal and ecosystem resilience and adaptation.</p>