No occasion can be more solemn than a funeral, and no attire can be too sombre. When thinking of funeral attire, a well-tailored dark suit generally comes to mind.
The watchword must be respect for the occasion and the mourners; a sober suit with white shirt and black tie is the only real choice you should make if attending the average western funeral service.
Depending on the circumstance and the persona of the principal mourners, a slightly less formal choice of men’s suit may be acceptable. Stick with dark colors, though – charcoal, dark grey or navy (brown is not normally regarded as appropriate) – and avoid loud ties. Conservative colors such as maroon and navy are acceptable for ties; it is best to steer clear of patterns.
Don’t remove your jacket, even if the heat is becoming unpleasant, unless the principal mourners take the lead and do so.