What happen to Euro if Greece defaults I have some money in Euros but living in USA. Today they are going to decide if the Greece will stay in Euro-zone.

I was wondering what will happen to Euro if Greece leave the EU. Or what is expected to happen?

I'm planning to exchange the Euros in August. Is it a good idea or should I do it right now or just keep the Euros?
Depends on WHY you have the Euros.

If you are saving up with a BMW or a holiday in France, it is very different to you holding them just hoping the Euros will go up.

I expect that if Greece leaves OR if Greece remains after a REAL agreement is made and KEPT TO, then the Euro will not be effected much.   But if Greece remains, but nothing changes in Greece, then the Euro will be dragged down by the next set of counties that think they can getaway with it.