March is one of those unpredictable months. We went this past March, first week, and our experience was great. We needed to wear a sweatshirt in the morning and when the sun went down. During the day the sun was warm and there was a breeze most of the time. I personally prefer to be a little warmer than cooler so I would've liked to wear jeans or leggings if I had had them.
Start watching the weather mid-February and pack when you've got a confident forecast.