The spring and summer storms can wreak havoc on trampolines. I grew up with one in my backyard for years and we never had problems with it blowing away.
We recently owned a trampoline for four weeks and it blew out of our backyard into the front porch of our neighbor's house. We had to replace the guttering on our house and our neighbor's home. We got lucky that was the only damage!
We just bought another one. We plan on using anchors but, if you have any ideas of how to keep the tramp from blowing away again, let me know!