> There's no such thing as poor weather, only poor clothing choices.
Where I live the heat index is supposed to be 108F with almost no cloud coverage. Riding a bike a few miles in the middle of the day is definitely risking heat stroke. It is without a doubt poor weather for riding.
And yet bicycles are very popular in countries where it is incredibly hot and humid.
Bicycling is more efficient than walking; you're generating less heat to move at the same speed, or you can move faster for the same heat generation, generating more cooling breeze.
I've ridden in over 100 degree weather during a heat wave. I dressed in the lightest clothing I owned, and arrived barely sweating.
My coworkers demanded to know how I'd arrived not drenched in sweat; after all, just walking from the bus stop many of them had gotten soaked in sweat.
Simple: I planned an extra ten minutes for my commute, and barely pressed the pedals...
If you are in good condition and wearing light clothes, sunscreen, and drinking plenty of water, hot weather is not a problem for bicyclists. Admittedly it takes a bit of work to get there, though, and most people are not willing to put in the work.
Riding when the temperature is 42C is "uncomfortable", rather than "not a problem", if you're seriously road riding. I suppose it's only "not a problem" if you're slowly tooling around on a cruiser...
Part of being in good condition is knowing your limits. If it’s that hot out, you will want to leave a bit earlier and ride slower so you don’t overheat.
Where I live the heat index is supposed to be 108F with almost no cloud coverage. Riding a bike a few miles in the middle of the day is definitely risking heat stroke. It is without a doubt poor weather for riding.