We were there 2 years ago in August and didn't bring any jackets. etc and wish we had. I would say this is a matter of very personal opinion but I tend to get cold. We were back last August and I packed all of us something. My kids never used theirs (young blood!!), but my hubby and I used our jackets at night. I especially found that some air-conditioning in restaurants was too cold for me. I would say to use your own opinion, if you are like me you may need something. Have a great vacation!!! We'll be there August 10 and I plan on bringing a light jacket for myself.
ENJOY!!!!!