not all weather effects collide with terrain, and even those that do, the resolution of the collision detail for the weather systems is not detailed enough to allow accurate collisions against square/bevel/tetra chiselled shapes, and will often act like they just aren’t there.
even water will be forced to pass through blocks that are chiselled on “both sides” as we cant encode liquid existing in one “half” of a block only; but this is still a much stricter condition than that of weather particles, so weather particles like snow/rain may well pass through terrain that is detail chiselled where liquids would not flow.
weather effects that do not collide, may still modulate by the sunlight, so if you have a completely enclosed with no-windows build, you will often get different effects too.
there is a plan to help improve the case of modulation by sunlight, so that it acts like the snow-covering effect where it is able to somewhat distinguish sunlight filtered through solid translucent blocks like glass/leaves vs unfiltered light which would help in those cases.
the collision granularity however is not currently in scope for improvement.