system
Given the following post, respond as if you're commenting on Reddit:
human
Why does the sun feel hotter on a hot day?

Today in L.A. it's hot, in the high 90s. I went out at midday and the heat from the sun felt unpleasantly hot, making me want to stay inside as much was possible.
 
A few days ago, it was maybe 10 degrees cooler. I went out at midday, and the sun felt pleasantly warm.  

I'm asking here about the direct sensation of the heat from the sun on the skin. It was the same season, same time of day, same location, full sunlight each time, no wind on either occasion. Why does it feel different?
gpt
Because you do not perceive temperature; rather you perceive loss or gain of heat energy. On the cooler day you were able to dissipate heat at a faster rate than on the hotter day, giving the sensation of being cooler. If it is humid this effect is compounded because you are not able to lose heat as effectively through sweat evaporation.