You can give me a call also cell # 099 163 267.
That Bouy that toby posted is located between Montevideo and Buenos Aires, but is not too accurate for the wind in Carrasco (a local beach in Montevideo) or for Punta del Este.
We are having excelent wind these days... an average of 18 knots with gusts of 20 at its peak.
give me a call once you arrive. I can recommend you some places to stay and visit with good conditions and the characteristics you are seeking.