From a website I looked at, the average rainfall for Bahamas in July is 6.21 inches. The high is in June at 9.17 in, and the low in Mar at 1.57 in.
In general, their rainy season starts in May and runs thru Oct. Their hurricane season goes from June - Oct.
However, when we were on the Magic in early Sept a few years ago, we didn't see any rain at all during day time. I know it rained overnight because the decks and our verandah were wet in the morning.