Yes, I would wear shorts, then have a sweatshirt, or light jacket for the evenings and the AIR CONDITIONING in the buildings.
As long as your core (your chest area) is warm, shorts will be fine.
I've even been perfectly comfortable in shorts and a sweatshirt down to the low 50s.
Add an extra layer to that and a hat, gloves, and warm socks and shorts are comfy in the mid 40s.
I know it sounds weird, but it works.
Remember the early 80s when walking shorts with heavy sweaters in the winter were the big style
If your really concerned, try those convertable cargo pants where the bottoms zip off. During the day you have shorts, then in the evening if you do get cool just zip back on the bottoms of the pants. They take up practically no room in the cargo pocket or day pack or fanny pack.
Carol