Is your feature request related to a problem? Please describe:
Currently, the default biome is "Ocean" which is all good except that whenever it rains it, well, it rains instead of snows. We're on some outpost on a barren frozen world. It would be really nice if it were to snow!

Describe the solution you'd like:
Change the default biome from "Ocean" to one of the snowy biomes (for example, "Snowy Tundra") so whenever it rains it'll snow instead.

Potential issues with the solution:
It'll likely not work for existing saves (unless there is some way to retrogen the biome or whatnot). The changed biome might end up causing spawning differences that need to be considered (for example, passive mobs perhaps?). It doesn't add a whole lot for the amount of effort that would go into verifying and testing it (although I think it'd be really nifty!).

Additional context:
If we start to have snow, then we can get snow layers built up, too, using this mod: https://www.curseforge.com/minecraft/mc-mods/chemcraft-snowfall which would look really cool and break up the look of the terrain. It would make spawns a bit slower when the layers got too tall, but given that there is nowhere else for mobs to spawn I'm sure that won't be too big of an issue. This could add a bit of quest-related lore in having to clear snow buildup every so often/etc.

No idea if it is possible at all, but adding some snowscape sounds (such as this: https://soundcloud.com/relaxing-white-noise/winter-storm-white-noise although of course with a licensing agreement that allows for it) would really complete the feeling. I've been playing with that specific snowscape sound playing in the background (turned down a good deal so it is kinda just a background noise and not overpowering) and it really adds to the feeling.

I'm just getting into the swing of this modpack, and the amount of effort you put into it is very obvious and extremely appreciated. Thanks!

Personally I find snow (the precipitation, not the block) really, really, really annoying, which is why I never went that route. Also, spawning rates and rules in an ocean biome are the closest to what I wanted for the pack. Changing to almost any other biome would involve a lot of changes that would possibly have a knock-on impact on quests, etc. without going to a lot of additional effort trying to override spawning mechanics that I think won't be adding much overall.

So while I get what you're saying about it being more immersive, I personally don't think the benefits outweigh the costs/effort on this one, so I'll not be taking this forward.

Thanks for taking the time to make such a well thought-out suggestion though! I appreciate that you have it so much thought too.