Strong wind blows UPVC Window shut.

[Jeff543]

Any solutions? Photo as attached.

 

[Notch7]

some friction stays have a screw adjuster

 

[matlob]

They should be friction hinges already so you should be able to just tighten them up to add more friction.
If it's an old window they have probably loosened

 

[ronniecabers]

As others have said the friction stays probably need tightening. You are looking for a small , usually brass looking , circular screw, always a flat head fitting, should be on the hinge where two of the legs slide in a black/grey bit of plastic