The amount of wind force or wind speed it takes to blow you or a person over will depend on the weight of the person or yourself.
For someone weighing in around 100 lbs of weight it would take around 45 miles per hour wind speed to knock someone over if they're not holding onto something.
For someone that weighs over 100 lbs it can take 65 to 80 MPH wind speed to blow that person over.
The heavier you weigh the more wind speed it will take to blow the person over.
I weigh 120 lbs and if the wind speed gets to 55 MPH it can begin blowing me around and if it gets to 60 MPH or above the wind speed can then knock me down if I'm not hanging onto something.