One of the most important aspects to keep in mind when you are using your projector screen is the wind outdoors. Do not take it for granted as if there are roaring winds outdoors, you may want to avoid using it. It really does not matter how well-designed and structurally sound the base and frame are of the model as if there is a high enough wind, it will knock it down. While designers will often test their models in high winds, once you get in the ballpark of 20 to 30 miles per hour you may want to consider getting your screen down as quickly as possible.
Truthfully, all you really need to do is monitor the weather to see if high winds are being called for. After all, it is always better to be safe than sorry.