Stopping cat climbing out of the window?

[MyCatWasRightAboutYou]

It's currently boiling here, so I have to have the bedroom windows open. One of my cats loves to sleep in my room, but he also climbs out of the windows. There's a little roof above the living room windows that he sits on. (It's about 10ft off the ground.) I'm worried that he's going to fall off. I've tried keeping him out of the room but he still gets in. Once he's in, he won't get out. (I've literally never met a more stubborn cat. He'll pull the carpet up by clinging on to it if he doesn't want you to pick him up.)

Any ways to prevent him getting out? Some kind of screen?

He's a cat! Of course he's not going to fall off!

Well the only way really is not to open the window

But the cat won't fall off.

Your cat won't fall off believe me. One of our cats climbs out the small fanlight window onto the drainpipe then up over the roof and down the other side all the time. Shes recently turned 3 legged and still does it!

One of our cats DID fall out of a window.
Google cat window guards. I'm thinking of flatcat.

A friend lived on the third floor of a block of flats - her cat Leroy used the window box outside as a cat litter tray!!

My parents have a screen over their bedroom window to stop the cat's jumping out the window onto the conservatory roof. Its a frame fixed the inside of the window and is kind of like a mosquito net, so air still flows through and it has hinges and a lock type thing on it so it can be opened.

Hope this makes sense lol

Flat cats brilluant

Gertie keeps throwing herself at the Flatcat screen trying to get out. Worried that the Velcro might give and she will fall out of the window (long drop down) Anyone else had this problem? Other than keeping window closed in this heat any idea wise MNs?