system
Given the following post, respond as if you're commenting on Reddit:
human
[Superman] How cold or hot does the temperature/environment have to be so not even Superman can withstand it?

Like hotter than the sun and colder than deep space, for example.
gpt
The sun is a bad example, because he solar radiation powers him up faster than the heat (or radiation) can damage him.

He has tanked nuclear explosions, but that seems to be close to his top-level durability, at least in most iterations. A nuclear explosion reaches a temperature of around 100,000,000° Celsius, or 180,000,000° Fahrenheit. It is probable, however, that radiation plays at least as much a role in damaging Kal El as the heat.

It's probably not possible to damage Superman with cold, as his body would be able to use stored solar radiation to warm himself. Cold, therefore, wouldn't harm him until his stores of energy were depleted, at which point he could be damaged like any human; frostbite sets in at around 0° Celsius / 32° Fahrenheit.