Grr, it'd be quite helpful if there was a "i don't fucking care how unusable the world is, _don't_ auto-reject!" setting in worldgen. It's pretty much impossible examining the effect of world settings when each world gets auto-rejected after ~5 mins of painfully slow initial generation.
The one world that miraculously was created at all was an extremely flat, no-temperature-variance world with a "temperature" setting of zero. Temperature rose continuously with latitude, from south to north. The southern 96 regions rows were tundra/glacier, the northmost ~16 were probably hot (couldn't generate it with a fort-able civ). The temperature map's a very regular black-to-grey gradient 4096 pixels high; the bottom ~400 are 000000, the top is cacaca. The gradient seems to be steeper at the outer edges (although that's speculative at the bottom) and flatter in the centre - on the "hot" edge, the colour values go up ~15 points over 100 pixels, while over the whole range from pixels 1500-2600 (1100 pixels total), they change by the same amount.
There's a notable natural temperature gradient between the "polar" and "equatorial" edges of the map, and afaik the "temperature" setting in the game applies a variation to this underlying gradient. Standard is 25-75, which suggests it's calibrated with 50 as baseline. How exactly temperature settings change that is hard to say, since creating worlds for reference is kind of difficult (see above). It's definitely possible to get far above +100 or below -200 °C with extreme settings, that much is certain.