July-September is the official Rainy Season here in central Mexico. When we flew into Guadalajara in early August, my first view out of the airplane window reminded me of scenes from Ireland. Guadalajara receives about 37" of rain per year, and about 33" of that falls during the rainy season. Beginning in October, get ready for almost no rain. During the dry season, Guadalajara gets about as much rain as Las Vegas, NV. I have seen pictures of this area during the dry season, and although the weather is Wonderful, the grass and many plants turn brown and there is a problem with dust.