Humid climates can create a easier pathways for spark to flow. If there are excessive resistance in the ignition system spark will take the easiest path and a damp environment will help.
Check the condition of the spark plugs, spark plug wires, distributor cap and rotors.
If the spark plug gap is excessive or the center electrode on the spark plug has sloped edges. It might be a good idea to replace all the above.
Check the distributor cap for build up on the inside of each cylinder terminal or carbon tracking. The same with the rotor.
Any resistance in the ignition system is going to weaken the strength of the spark and/or redirect away from the spark plugs causing misfire, no start, partial firing, etc.
Let me know what you find.
Monday, January 20th, 2014 AT 7:23 PM