No need to wait for a rainy day. Check it any time with the aid of a hose or bucket.
Dry days are best for making effective repairs. You can detach the relevant fitting and then you only have to wait for the hole to dry out, and repair it on the same day, rather than finding your leak, then then continuing to suffer water ingress while waiting for a dry day.
The membership association for owners of Dufour Yachts