Wearing my formal dress to a wedding

I just found out that I am invited to my boyfriend's cousin's wedding at the end of August and I was thinking maybe I should wear my formal dress instead of going out and buying something else because its just one day.
Would this dress be wedding...

appropriate?

I like it, but do you think black is an appropriate color to wear to a wedding? And you should find out if the wedding is going to be formal or non formal.

Do you know what time the wedding is? evening weddings it is usually fine...

I really like that dress I think it would be perfectly fine. There are actually a lot of people that wear black to weddings. It's normal to wear black to a wedding.