Keeping cats in at night and open windows

[Lindy2]

We got our lovely rescue cat in November. She loves going outdoors all day but has always been happy to come inside at around 5pm when she has her tea and heads upstairs to bed. We then lock the catflap until around 7am the next day when she heads off outside again.
I would prefer she carried on staying inside at night (we are in an area where the cat killer has struck several times and recently too 😢)
How can we do this in hot weather though? She loves an open window and will almost certainly be out and onto the extension roof at some point during the night.
She went out our loft velux several weeks ago and ran around on our main roof whilst it was covered in snow. We've kept them shut since but can't do that forever.
What does everyone else do?

We've just moved from a basement flat to a house, and one of our cats has discovered a love of tightrope-walking on the ledge outside our bedroom window. For now I've tacked up some mosquito netting that we had lying around, but later I'm going to buy pet mesh (have a google, it's not a brand name and I think lots of companies make it) that's more durable. It velcros onto the window frame, so you can take it down when it's not needed.

We have a huge ceiling fan over the bed, summer duvet so we don't get hot at night.

For the rest of the house I leave all the trickle vents shut and blinds shut like the Australians do. I open the loft hatch to let heat escape up into the roof. We don't open the windows till the temperature drops.

He uses the utility room to sleep in overnight so I've bought a mirror foil to stick to the outside of the back door glass to stop any heat getting in that room, it's south facing so gets sun all day.

Thanks MasterLeonard. Pet mesh sounds a good idea. I'll Google for more details.

Have a look at Flat Cat window screens. They are brilliant, and as a bonus keep all bugs out too.

Thanks all. I'll look into these options.