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.