A reminder, folks - where there's service changes on the railway due to very high temperatures today, it's because the railway isn't immune to the laws of physics. "But railways in hotter countries cope...". Yes, because they stress their rails for a hotter temperature range.
As it's heating up in most places, here's an explainer why a railway might want to err on the side of safety rather than keep things running normally.
All of our infrastructure - rail, roads, power, water, the lot - is designed to operate within a certain temperature range...