JS99Z

I have a 99 Z and the passenger side park lamp keeps getting water in it. I bought a new one and installed it. Now a month later the new one is doing the same thing. Is there a fix for this? Can I dry it out with out removing the lamp it self. The car is rarely in the rain, and when I wash the car its not like I concentrate water directly onto the lamp. Whats the deal are the lamps not water tight, or is it just moisture building up?

Thanks