Things are much more laid back and low key in the summer. An elegant shirt or a cuban guayabera will do fine for a restaurant or club. It's a good idea to take a mix of long and short sleeves. Keep in mind that even if it's incredibly hot outside, many facilites have the AC full blast. You will see many men with jackets and long sleeved shirts at night, especially if they are coming straight from work. If in doubt, wear a long sleeved shirt and you will not be out of place.
** Note: The original information for this thread came from the following forum thread:
