80 F (26.7 C) to 90 F (32.2 C) with low humidity. I like heat, but relative humidity over 60 is horrific for me. The ideal day would be 85, cloudy (I would even take partially cloudy), and low humidity.
Anything below 10°C. I cannot stand the heat. My heart can't take it. In all my years, I have never been able to adjust to it. My body has a very difficult time adjusting. My eyes are photosensitive as well so I love winter when it gets dark earlier and it's nice and cold.