There's no rain issues with GruppeM. Can't say the same if it's hailing or something, but the rain in Aus isn't that heavy that it will affect the performance of a GruppeM. Hosing water down the snorkel of GruppeM didn't seem to affect mine but with saying that, I don't recommend it just in case But if you are worried, GruppeM provides you with a rain cover for your snorkel which you can attach if you want to