Is your primary concern for glass breakage or for him crawling out the window?

The lower panel appears to be fixed, and is the upper one fixed and one operable slider?

How tall is the lower panel?

I am wondering if a 4 year old could even open that window without help.

Do all three panels have a logo (etching) in one corner saying tempered or safety glass?

Get someone to make for you the equivalent of an upholstered padded headboard with both sides showing attractive fabric. Secure into the window frame So your child can’t get it out. Before you get it made measure to make sure it is high enough that a child can’t drag a chair or box over to stand on and then be much taller than the barrier.

you could also build a box of slatted wood if you didn’t want to block light

I would frame the lower window in wood and make a contemporary "plantation" shutter that is fixed to it and inoperable, but removable with removing the frame.

I installed a gate. Made me feel good that people could see the safety modification.

The gate was made for dogs, heavy duty opened both directions.

Do you have a fire escape ladder for that window? Bedrooms are required to have a window escape.

I would get the window guards, you can google them. Some don’t look bad at all! For me it is a safety issue and I just would not want to take the risk of an accident. Think about situations such as when he has friends over. I tend to be very risk averse and that is my suggestion.

jim mat

I have owned many second and third floor bedrooms with windows and no ladder or fire escape . I am puzzled by your comment

Is there another room for the little tykes bedroom?

IMO safety first but why is this the space for a toddler and why this choice for anew window if this is the only bedroom for him. IMO no matter what you put in front a kid will figure out how to move it or get over it .I think right now the only thing thta would work is a installed type of grid system that is attached to the walls and not able to be removed without tools . It could be attractive with some imagination similar to the wood ones in the pics above .

I would agree with gate system attached to walls that can’t be moved by a toddler, but one that does not interfere with egress

It should not interfere with ingress as well. There are code requirements in the the IRC code that be taken into consideration.

Ital mover, what would do in a fire and the only egress was from a window?

Jim I don’t want to clog up this thread but 99% of multistory owner occupied single family residences have bedrooms upstairs without having ladders or fire escapeS. Obviously it is legal.

It is very legal, I did not write “not having a fire escape” was not legal...I wrote bedrooms are required to have a window.

I ”tried to” recommend upstairs bedrooms have an emergency escape ladder. I do. In a red bag under the bed.

@User This is what Jim is referring to, and it is recommended especially for children who would have a tougher time safely dropping out of a second story window. It is recommended to have one if you have children in upper floors. We (guiltily) don't have one for ours but I have considered getting one and probably should.

OP: you haven't said what your actual concern is. Are you worried about him crashing through the lower window? Or are you worried about him opening the upper window and climbing out? If the first, then put a toy chest in front of it. Get one with a sloping top if you don't want him sitting on it. Or get a comfy reading chair. If the second, leave it be. Anything you put there will become a climber.

I'd put up a gate, or put him in a different room. Really there is no other "safe option".

I see a grill outside the window on an outside wall. How about attaching a grill outside the window like that? It can be removed at a future date...Safety is more important for your little guy than how it looks. You mentioned the window was over your front door.....if you are worried about how it looks, put a grill storm door on your door also..

I think the grill you are referring to, is a fence gate. You can't put a grill over the whole window because there has to be an egress in a bedroom.