Heatwaves are caused by lack of rain and the following draught. Think about the dry Sahara desert. Extremly hot by daytime, and freezing cold by night. There is no water in the ground keep the temperature down in the day, and no water to keep the temperature up during the night.

Thanks

People forget. Even when it is just a few weeks ago. Let alone when it is more than a century. Thanks Tony, for continuous work