Oh poor baby! Jackson is not afraid of the dark but he is TERRIFIED of rain lol! I'm putting the sprinkler on now cause it's raining alot more & want him to know hey it's water your not sugar you won't melt!! He's gotten better and just does his business extra quick. :P Maybe have lights put out in the back yard & the first couple times have your hubby & you go out there with him so he feels safe! Jackson is 5months old & holds it over night with no problems but I do keep him in a playpen at night so he doesn't have an accident all over the house! He loves it & we have a great routine!
Good Luck.