The second open water swim I did was during a torrential rain storm. On the way there I was adamant I wasn't going to get in the water, but the absurdity of 'not wanting to get too wet' struck me so I HTFU and got in anyway. There was no current to help though - it was at a dock 
I think that was the swim where I contracted leptospirosis though, so swimming in churned up water might not have been the brightest idea...
