Alarm going off in rain

[Yorkshire Midge]

My 09 plate Cooper convertable alarm sometimes triggers in medium-heavy rain. I see this has been a problem in the dim and distant past with first generation models but has this weakness been carried forward into the second generation models too?

TIA, Midge.

[Millieminx]

I'm also having the same problem with my 59 plate JCW convertible. Seems to only happen at 2-3am in heavy rain... Heavy rain at other times doesn't trigger it and it doesn't go off on dry nights. I've only had the car for six weeks and its happened three times.
Any help would be appreciated

Millie

[Yorkshire Midge]

I'm pretty sure it will be ultrasonic detectors causing it to go off, and I think you can actually disable them when you lock the car if your problem is serious enough (check your manual) but it rather defeats the object of having an alarm if we have to turn bits of it off! I suspect the night time occurences might be a co-incidence. Mine was in at the dealer a few weeks back and whilst it was in their car park, the heavens opened and it rained so hard I'd have put money on it gonna go off and it didn't. Couple of days later in lighter/medium rain it did, so it isn't consistent for me (both daytime). It can go several weeks between occurences too.

I was mulling over shutting the air vents when I leave the car, in case them being left open allows a fraction too much air movement inside when the fabric is flexing slightly as it gets pelted. Might be one for you to try?

Failing that, if I have a minute, I was going to turn a hose on it and see if I can actually reproduce the sort of effect that triggers it.

[Millieminx]

I suspect you're right about the daytime/night time being a coincidence as its just gone off this afternoon in heavy rain.
I've occasionally disabled the alarm as you suggest but it does seem to be pointless to have an alarm I can't use.
The air vents idea isn't a bad one - I might give that and the hose pipe a try