September would be a better bet. It is usually warm in September. Most days in may - it usually won't rain but it will probably be cooler.
September always proves to be a beautiful time of year in terms of weather. I wouldn't worry to much about wind. With a beach wedding in May you will have a strong chance of good Coleman May Gray and still some chili evenings. Hope this is helpful :)
You should check out the Chart house in Dana point.
I had my ceremony outside overlooking Dana Point Harbor in the middle of September. It was perfect weather, sunny, clear, slight breeze. May has a much higher chance of being gloomy and cold.
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