What to do?!

I still have a booking for Rio next week, but the weather looks awful:

http://www.accuweather.com/en/br/rio...-weather/45449

Wednesday looks to be a write-off which is fine, Thursday and Friday show promise. I'm not sure how accurate the forecast for next weekend will be though. I'd be disappointed if there were 3 or more days where the beach was a no-go on account of the rain.

What would you do in my shoes... go next week to Rio and hope there's enough sun for the beach, or wait and go in mid-May?

Thanks!