If you want the full experience of this modpack, you will have to:
Play on hardcore
Use the same custom world config as the one world provided
At the very start of a new world open the questbook and activate the crazy weather
If you die, try again, and again, and again. This is really hard modpack, so it should take you at least 3 - 10 tries before you survive your first day.

Credits to modders:
Snownee_ for snow real magic

Final tips you should probably know before you die 30 times over:

- You cant chop down a tree with bare fists, you need flint axe for that (for more information about early progression, check no punching trees modpage)

-
Going underground wont save you from cold

- Hiding from snowfall greatly reduces your cold buildup

- You can craft flint from two rocks by placing them next to eachother in crafting grid

- The only mobs on the surface are rabbits, sheep, polar bears and rare Frosmaw, a giant monster that fortunately sleeps and does not attack unless provoked
- Durring night there are no monsters on the surface, except for Grue that will kill you if you are in total darkness for too long, so dont bother making walls the first night

- Lava is a great permanent source of heat, but it cannot be moved, replaced and spawns lava monsters sometimes

- Create as many fire starters as possible, fire starters cannot light up camp fire (only flint and steel can) so just light up the ground and use the 5 seconds of fire to heat yourself

- There are no beds, you have to survive the freezing nights

- And finally once you manage to overcome the blizzard cold, dont start thinking it is over since there will be after the seventh day invasions of various snow monsters that will increase in difficulty as you progress.

Dreaded Frost