Curtain sway causing false alarm from motion detector fix

Does anyone have a way to prevent false alarms from the motion detector due to curtains blowing in the wind. I keep a window or two open at all times in a couple of rooms during the cooler months when I am gone to keep it cool due to electronics (mostly computer room). Not able to run AC as the air outside is cold enough to cause frost on the line. Those rooms have motion detectors and we have 60mph+ gust of winds at sometimes which blows the curtains and activates motion detectors causing a false alarm. what is the best way to remedy this while still being able to have motion detectors along with security camera in the office/computer room to have it covered by both simplicam and standalone motion detector.

I would love to hear ideas and fixes that actually work. I have the motion detectors placed in the corner of the room and sensitivity set to medium on both. they are button side up