No. Unfortunately, in any salt cellar the salt is open to the air, so it is not an effective vessel for keeping the air out, and thus not an effective vessel for keeping moisture out.

A salt cellar is a piece of servingware that dates back to when the salt on your table was always going to be much larger, around the size of chunky sea salt or an extra large flake finishing salt. The few hours it would be out on a salt cellar for your kingly feast wouldn't matter, and leftover chunks would be stored in an airtight pottery crock. The majority of the salt in your home would be in block form, stored usually in a barrel or larger crock. The salt would then be chipped or grated off of the block and placed into the salt cellar for serving.

Tl;Dr a salt cellar is servingware like a platter or large bowl to be used for a few hours at a time, not storageware to hold your salt for weeks or months. If you want to store your salt and are in a place humid enough to worry about moisture, get an airtight container like a mason jar and put a few grains of rice in the bottom.