I think it's possible to use console commands by script. I tried LURK for testing purposes and it modified my lighting settings using console commands (IIRC).
I think it's done via script, though I don't know if it's done on the fly or at game start, as I never needed to look at that.
Also, I remember that it modified my "user.ltx", so if you're thinking about messing with the player's settings, you might want to save their config first so you can put it back afterwards, because some people might not like losing their precious "user.ltx"
I'll check the mod tonight if you haven't and tell you my findings about this.
Thanks for your reply. As far as I know LURK does about the same that I do in Dynamic Shaders to control the dynamic wet surfaces effect, changing certain settings in the user config in order to "activate" a certain shader behavior. Unfortunately it is not possible to change "internal" weather settings using the user.ltx / console commands, that's why I'm asking for an other script way to do such.
Something considered impossible is only something that hasn't been done yet.
You can achieve a more temporary change using weather effects from set_weather_fx instead of set_weather, but that's not much better. All of the engine interface functions are listed in lua_help.script; I've never heard of anyone doing what you want, and a quick search for some relevant keywords in there doesn't turn anything up, so I'd hazard a guess that it's not possible.
If you really want to do it you'll just have to get your hands dirty with the engine source.