My Sirio 1/2 wave SWR goes a little too high on the upper frequencies of use when it rains, and I'm not too happy using an amplifier when like this.
When dry, the SWR is good and in the range of 1.1:1 to 1.4:1 from Mid 1 to UK 40. When it rains, I see just under 1.1:1 on Midband 1, to 2.1:1 on UK 40.
I've heard a few complaints about this Sirio Antenna SWR changing dramatically in the rain, and even though I've mitigated water ingress by using self amalgamating tape, etc', it still happens.