Can stuffy, as in a stuffy room, be used to describe clothes?
"This shirt is too stuffy to wear in the tropics." No? Any suggestions?
You should consider thick. It means heavy in the context of clothing. Look at the example sentence for thick from ODO below which is quite similar to yours.
"This shirt is too thick to wear in the tropics."
1.1 (of a garment or other knitted or woven item) made of heavy material: ‘a thick sweater’
‘Mr Whitby said the man was quite large, wearing a baseball cap and a thick coat, which looked out of place in the warm weather.’
Also, heavy may work.
2 Of great density; thick or substantial:
‘Aching from head to toe, Clara pulled the thick, heavy robe around her waist and cinched the belt tighter.’
‘Most of the seated figures wear a distinctive heavy robe with thick, rounded borders.’
Agree with spagirl. "Breathable/Not Breathable" is the term you're looking for ventilated clothing. Or I would say the clothing is "too heavy" or "too warm" for the tropics.