I'd be more worried about those type of clamps than rain, I had one randomly break once and hit me on the side of the head.These connections are designed to be usable in the rain. That said, tehre have been cases where Vauxhall Ampera (=Chevy Volt Mk1) sockets on the car shorted out internally due to damp getting in at the back. GM fixed this by applying sealant round the back of the pins. There's always the possibility of a plug getting impacted/hit accidentally, and the whole thing's bound to flex, ever so slightly, so when it's raining I simply clip a stout plastic bag to form a tent over the chargeport ares. Can't do any harm, and may do some good!