Re: When it rains...........
Dirty wires, cap, coil etc can do it.
The dirt - even a slight amount mixed with the oily film that collects on them is conductive enough, then a small amount of moisture - even fog, can cause the spark to go to ground.
Paint thinner on a rag works well. Clean it all squeaky clean - wires, coil wire, coil, & cap.
Test by spraying everything down with a spray bottle of water. Listen for any engine sound change where you missed a spot.
DON'T USE WD-40 -- it may force the water off temporarily, but WD-40 attracts water! That's why everything you put it on rusts fast! It's just kerosene and perfume anyway.