I find the inaccuracy of the temperature reading on my bike computer surprisingly useful. It may be right out for meteorological purposes, but it's generally a good indicator of how I'm going to feel after a couple of miles when I get back on the bike after a stop.
I've seen it read over 40C, but only within tent. (Where it functions as an indicator of how I'm going to want the openings of my sleeping bag configured once my lard and feet have warmed up.)
When it got to this point (Germany, 2016), getting off to take the photo was a challenge: