For attending an Opera in the afternoon, you should wear dress slacks and a dress shirt if you are a male. A female should wear a casual dress.
business wear
Neat casual is fine. Many people dress up to one extent or another, but at matinees it's not expected.
Opera glasses <joke> Wear what you would wear to the opera in Seattle / New York / London / Paris / etc.
You should wear something presentable to a matinee opera, but less formal than for an evening performance.
There are numerous kinds, but the basic types are - Grand Opera Comic Opera Serious Opera Opera Semiseria Opera Cornique Opera Verismo Singspiel Operetta Chinese opera
business wear
Neat casual is fine. Many people dress up to one extent or another, but at matinees it's not expected.
Opera glasses <joke> Wear what you would wear to the opera in Seattle / New York / London / Paris / etc.
soap opera Talk show News
i usually wear nothing
You should wear something presentable to a matinee opera, but less formal than for an evening performance.
Yes, you can wear green to an opera, unless you're a man and it's the premier performance. Then it's black and white.
Evening Gowns and Tuxedo.
clothes
Late afternoon. You want to wear something dressy, but not evening wear. It is too early in the day for evening, but late in the afternoon for morning.
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no wear neon pink