Even if the coilpack is dry on the outside it'll probably have lots of moisture on the inside. I used to have starting and running problems at the first sight of rain, checked everything over and over and decided to bite the bullet and buy a brand new coil for £80 (RAC 1 year warranty). It's been perfect in the rain for months now, it's finally an issue I no longer worry about

Check you've got no water inside the distributor cap as well by the way
