We've seen 40 degrees in the Netherlands in recent years. As well as below -15.
Have you seen it for practically a month straight? 40 degrees is average high in Las Vegas from June to September, and it’s only getting below 30 degrees from November to March. In Houston, Atlanta, Miami or New Orleans, it’s above 30 from May to October, and it’s even worse than in Vegas, because these places are much more humid, making the heat less bearable, as sweating doesn’t really cool you off.
Seriously, climate in Netherlands is in no way comparable to most of US.
The non-coastal regions of the US are more like Eastern Europe where you can get 35 degrees in the summer and -20 in the winter.