My view is that it all depends on where you're from and what you're used to. I assume if you're from the south, March may be chilly (as noted above) - if you're from northern states, not so much.
We're from Canada, where March trips are a break from snow and highs in the 30's. For us, 60 = shorts/t-shirts, 65 = pool weather and 70 = air conditioning.
On our last three March trips, we put on hoodies at night while walking around the parks (still in shorts) - but at the same time, see people with touques and gloves on, searching for coffee and hot chocolate.