I work in an extremely hot and humid climate, and wear a variety of things. My "daily beaters", if you will, are linen suits that I wear as two or three piece according to my mood and the occasion. But sometimes it's a wool suit, my shirts are cotton of varying weight, and my socks are always worn and always over the calf - cotton or wool.
So the answer is this: sometimes you get hot, and it's unavoidable, however wonderfully summery your office attire. But let me share one word with you that is the solution to all heat problems: U-n-d-e-r-s-h-i-r-t. Yes, it's an extra layer of clothing, and yes, you will still feel hot. But a close-fitting cotton undershirt with T-shirt sleeves is your best friend in warm weather, because you will never get that crumpled sweaty look on your shirt, and can even take off your jacket now and then without fear of what the world might see under your arms. So yeah, undershirt. And a stick deodorant. And if you're hairy, trim your armpit hair too, so your deodorant actually arrives where it's needed.
Today it's about 100F and 75% humidity. But nobody will see me looking sweaty, even if I have to take a little walk. Being hot is unavoidable, but that's the secret to still appearing cool.
Very good advice, mimo. I also live and work in a very hot, though not always very humid, climate and I've learned that wearing an undershirt does indeed help. I also found that wearing very lightweight shirtings is not the best, either. Especially if you do not like the idea of an undershirt. As mimo says, you're going to be hot anyway, so better make sure you're still looking cool. Combining heavier shirt cloths like oxfords or dobby with fresco wool or linen suits may sound counter-intuitive, but I've found it works very well to maintain a crisp enough look throughout the day.