stlhdr1 I've fished Ixtapa/Zihuatanejo for a few years now. I've seen few marlin, but sailfish are caught all winter months. We have done better in early December than in the spring. I don't know if you already have a guide or not, but a good guide is a big part of your success. Some of the guides down there aren't fishermen, just lucky enough to own a bost. I highly recomend Carlos Olea. His english isn't so good, but he can sure tease those fish into a frenzy. If you want his Info send me a E-mail. The fisherman that don't go offshore generally just catch small game such as bonita. Carlos wants to catch billfish and he will try to talk you into going offshore for them. As for things to look for BAIT BAIT BAIT and birds feeding on Bait.Fish fresh bait and have lots of teasers crashing on the surface. Weather well the weather doesn't change much down there, atleast not enough to change fishing conditions that I've seen. I hope that this helps answer some of your questions. Good luck, your gonna have a great time.
P.S Don't hire a guide if they approach you. the good ones don't have to go around selling themselves. Guides down there are like cab drivers in Jamacia, (plenteful and mostly crooked) So beware.