You did ok getting 1 out of 2 days. In the June to August time frame you can count on about 30% of the days over a 10 day period getting blown out. The shorter the span you choose the higher odds you have of not diving at all, just because you picked wrong day(s). As soon as you leave it might be fantastic for 3 days in a row.
In a nutshell here is a explanation of how the season progresses:
Spring to early summer: Cold fronts are the weather makers. They come through in 7-10 day cycles, making for 3-4 days of rough weather.
Mid Summer: The Bermuda high dominates the weather creating extended stretches of strong SW flow. Some days are rougher than others, some keep you in port.
Late Summer to early fall: Hurricane season...the weather is great when ever a named storm is not around
Fall: Cold fronts dominate again, but the water is warm and the days after a cold front settles out can be the best diving of the year.
Winter: BRRRRR but you sometimes can get the rare lucky day.
I wrote about this in a little more detail in this blog...
Spring Weather Patterns in NC | tortugacharters.net
Here is a blog I wrote about a 10 days stretch of beautiful weather last August...
Another Stretch of Beautiful Weather | tortugacharters.net
Bottom line is, come stay a while. You will get your diving in MOST of the time. There is a lot to do ashore when the wind blows.
And remember...nobody on the boat wants to go diving more than the Captain, so if the trip gets called then you should be thankful, not upset. The old saying goes
"It is much better to be on the land wishing ye were at sea, than to be at sea wishing ye were on the land"
