Well, this isn't a rose that will curl up and die at the first sign of moisture. The blooms on mine came though the rain just fine.

Two photos are attached. The first shows the bloom that was beginning to open when the rain hit. At the time, it was about as developed as the bud in the background, at upper left.

The bud in the background was at the stage where the sepals had peeled back, but the petals hadn't started to unfurl.

Both then got walloped by a goodly dose of precipitation over the course of a couple of days. It doesn't seem to have bothered them. A couple of sunny days later, they're both looking good.

I expect I will eventually find out which conditions do cause balling for this rose, but it hasn't happened yet, and obviously Aotearoa will handle some rain without it being a total disaster. Which is nice to know. :)