I think I'm too late in responding to your question, but I'll give it a go anyway. Honestly St. Lucia is the last Caribbean island I would visit if you're wanting to go to the Caribbean. I last visited when I was 16 with my family on spring break in 1999, and would certainly not return for a honeymoon. The scenery is out of this world in pictures (and is still very nice when you are there), but the weather is dreadful. It was extremely hot, and the humidity was around 100 percent. The moment I stepped out of the villa where I stayed (it was the Windjammer resort as I recall) I began sweating (it is also horribly sticky). I am in good shape and do not sweat very much (except when I'm exercising), but it was intolerable just stepping out the door. The water was so hot you can not cool off either. It is very mountainous there and are very few places where you wont encounter steep hills (and the island seems very small as well). The only good side I would say is that I heard both the weather and the water temperature are much more reasonable in August then they are in the late winter/early spring (cant be certain though). You might have some better luck in August. As for Jamaica... The last time I visited was when I was 10 years old and so I cant say for sure about it. But I'm guessing the weather is a little better in August as well. The one thing I do know is that if you are American (especially Caucasian), natives of Jamaica might not be very friendly (I have know there is a history of that as well). But my favorite Caribbean island I visited was the Bahamas. It is beautiful and the waters are pristine (and people seemed very friendly there as well). My only concern about the Caribbean islands in general is that they've probably become a lot more crowded in the last 5-10 years. But I'd definitely consider traveling in August. If you don't want crowds, avoid spring break if possible.

Thank you Linds182 for your input. My family of 3 and in-laws are deciding on vacationing in August. We have kicked around different Caribbean areas.. I have not even thought of the heat & humidity during this time of year. I think I'm back to square 1. Maybe just stay in the states, LOL...

Don't know why people think the Bahamas are in the Caribbean. Bahamians would be horrified.
The climate will be the same in Jamaica or St Lucia in August and the same as anywhere else in the region at that time if year. Problem is with Jamaica if you go too early in the year, although the temps are more pleasant, the sea can be a little cool.

We've been to Jamaica in a November and December and didn't have any issue with the sea or pools being cool. Actually, the temps were perfect for that time of year. Not to hot or too cool. I would think August it would be more hot and humid. We had issues with pools being to cold to use in Mexico that time of year.

Have been to the Bahamas in a September and barely missed getting creamed by a hurricane. I do agree that the beaches are gorgeous, but Nassau was a disappointment. The out Islands are a better option.

Even in the US in August, you will have to deal with hot and humid weather.

I am glad that you finally decided on St. Lucia. When you get there and thoroughly enjoy it you will then reflect on some of the misinformation provided by some of the above persons. It is the most spectacular island in the Caribbean although Jamaica does come close in some respects. The difference is that St. Lucia is smaller and you therefore get to see a greater variety of scenery within a much shorter time frame. There is lots to do there too. The weather in the hurricane season is some of the most incredible. Hurricanes are hit and miss and don't hit all the islands all the time. This season there were NONE! I have just returned from St. Lucia. I reject the comment made against Jamaicans by one of the above contributors. The response that one gets from your hosts depends to a degree on the courtesy that you also show them as visitors. Treat people the way you would like to be treated and unexpected wonder can sometime result. Enjoy St. Lucia.