I really doubt there's any full suit that isn't unbearably hot for me. I'm often wearing a t-shirt and shorts complaining about the heat while others are wearing sweaters and shivering. Casual attire gives you a range of options, whereas formal dress seems to always require layers.
It requires three layers when often one is more than sufficient. It comes with a noose that fits tightly around my neck. It comes with shoes that have no grip. To keep the cuffs just-so, one wears tight bands just below the bicep. The pockets are easily distended and thus barely useable (I miss the 80s, when a distended suit pocket was the sign of that most ugly of status symbols, the mobile 'phone). Easily smutted, one must carry an umbrella or yet another layer to protect it from the rain.
If it is appropriate for you to wear a suit for an occasion (outside of church, weddings, and funerals), then you are likely making enough from the position to pay for the suit.
This doesn't apply to me, but couldn't this be a catch-22? To get a job/social status where you're making good money, you need to get a suit, but you need the money for a suit in order to get that job.
Also, you could just be averse to a perceived waste of money, even if you could afford it (my case).
