If you love someone enough to marry, any month is good.
At least one month before the baby is due.
Well, I chose June. But that's just me. My sister picked October. It really depends on what sort of setting or landscape you prefer. I enjoy hot weather. I picked a clear sunny day but everyone said it was sweltering hot...I didn't mind it. :) My sister picked a day everyone complained was cold, but my wedding was outdoors and hers was mostly indoors....she enjoys the fall colors so she picked fall. So it's a personal decision. It somewhat depends on if you want an outdoor or indoor wedding too. Some people like to get married on valentine's day or christmas...personally I hate cold weather and so I would never do that. People sometimes get married on their anniversary of meeting/first date or whatever but ours would've been very cold weather.
August, September or October, it isn't warm nor cold.
Whatever works into your schedules. lol
Anytime in the spring, it's beautiful
September is fabulous!!! The weather is still nice, just turning to fall, and the wedding bookings ease up a little bit and are easier to obtain because you are no longer in the heaviest booking season of the summer months. Go for early September right before the kids have to go back to school, just in case you have to fly relatives in from out of state...otherwise they may not be able to attend.
November.. the air is crisp and the Late Fall colors are beautiful. Deep russets...dark reds..jewel green... wheat and chocolate brown... It's a lovely month! Plus you get great discounts for skipping "wedding season" June-August
depends where you live and if you want an outdoor ceremony.