You would only have to be weather proof to the extent that your wing is weather proof. Paraglider wings generally don’t perform when wet as opposed to a bit damp. I speak from experience here. One afternoon I was flying from a peak in Slovenia when I was caught in a brief shower. I went into rapid decent mode and induced a horseshoe stall.
When I tried to recover the wet fabric surfaces had stuck together! I was pumping those brakes like I was trying to fly by arm flapping alone! After a while (which felt like hours) the surfaces reluctantly peeled apart and I landed, well short of the field. Strangely I’ve been more careful of the weather since
Paul in Oz