Yes i do have obse and no i dont have weather mods.
Atmospheric Weather System (AWS), Enhanced Weather (EW) and All Natural (AN) all support darker nights with INI configurations (no extra plugin necessary.) However...
Darker Dungeons and Nights Mods Pack - http://www.tesnexus.com/downloads/file.php?id=14118 <-- LtBD is better for darker dungeons, but the darker nights mods have not been replaced. You can get more degrees of darkness through weather mods' INI files, however. If you get All Natural, you can use its darker nights option (through the INI) and Real Lights for the full "dark" experience (in addition to LtBD.) You will need torches or some other form of light to get around at night or in (should be) dark places. AN completely incorporates the other two weather mods mentioned above, as well as Natural weather and Real Lights. Do not install the original mods with it (and you should not install multiple full weather mods together anyway.) You can find links to all of the weather mods I have mentioned on the Downloading Mods page I linked earlier.
Oh, and I mentioned OBSE because that is required to use the darker nights INI options.