Yeah, I sympathise! Out 3 month old pup has just met rain for the first time since we have had him! He was NOT amused! He also took one look outside and put his brakes on, reversed and headed back in the house!
I got a large umberella, went back out and held tghe umberella over him right by the side fence ...it worked eventually! Guess who got wet though?!!!
Good luck!!