[foobarchu]

Brightness and color temperature are orthogonal. The dimmer switch only controls brightness.

[Marsymars]

There are, however, some dumb LED bulbs that have built-in circuitry to warm as they dim. Some of them even adjust the temperature based on the dimmer switch setting without adjusting the brightness for part of the range of the switch. They're quite nice, I use them in various places.

[pigpop]

Incandescents are mostly in the red/warm end of the spectrum anyways so you don't need to change the color temperature at night.