Using a relative surface air temperature threshold for each grid location in ERA5, I can define the start and end of the warmest season of the year, a.k.a. summer. Building on the prior works in this line of inquiry (Park et al 2018, Weller & Park 2020, Wang et al 2021, Lin & Wang 2022), I've found that the rate of increase in summer length since 1990 is 50% higher than previously reported. Seasonal transitions are becoming more abrupt. And, the accumulation of heat in summer is 3x faster since 1990 than over 1961-1990. This work was recently published in Environmental Research Letters.