Can I just not wear pants?

It's only the beginning of March and it's 78 degrees out! Normal weather where I live would be like 40s and 50s at the warmest. I do not have clothes that fit for this kind of weather and don't want to buy anything new when I'm already 34 weeks. Seriously considering just walking around in my underwear. I might cave and put the a.c. on. ... Can't wait for this baby to come!