Depends on where you're from and what type of weather you're use to. lol Today it is 27 degrees Celsius, which is crazy warm for us in the middle of winter (Alberta, Canada) and would definitely be t-shirt and shorts weather. When we are going they are calling for 21, which is still very nice and would probably still be t-shirt and capris or shorts.
When I was there in February last time, it was unseasonably cool and we were in jeans and hoodies most of the trip. Doesn't seem to be the case this time around though but we will be prepared with hoodies for the night time.