Falls from windows involving young children rise sharply in warm weather and fall away in cold. The pattern is not about children's behaviour changing seasonally but about when windows are open.
Ventilation is what opens the hazard
A closed window is a wall. Its safety comes from being shut rather than from any feature of its design, and that protection disappears the moment the weather turns.
Homes without air conditioning open windows for longer periods and open them wider, and upper-floor bedrooms are often the rooms left open overnight and unattended during the day.
The seasonal shape of the data therefore tracks temperature closely. Injury services in many countries plan for it in the same way they plan for other seasonal patterns.
Insect screens are not barriers
A screen is designed to stop insects entering and to be removed easily for cleaning. Its frame is light, and it is usually held in place by friction or small clips.
It carries no structural load and will detach under the weight of a leaning toddler. From inside, however, it reads as a solid surface to a child and often to an adult.
This is the most consistent misunderstanding in this category of injury. A screened window that is open is, for practical purposes, an open window.
Furniture supplies the route
A window sill is usually above a young child's reach, and the fall requires something to climb. Beds, sofas, chests of drawers, toy boxes and cots placed beneath windows all serve.
Placement is driven by room layout rather than by risk assessment, and beds are frequently put under windows because that is where they fit. The hazard is created by ordinary furnishing decisions.
Moving climbable furniture away from windows removes the route without removing ventilation, which is why it appears first in most prevention guidance.
Height, surface and outcome
Injury severity rises with fall height, but serious injuries occur from first-floor windows as well, and head injuries dominate because a small child's head is proportionally heavy.
The landing surface matters. Falls onto grass or soil have different outcomes from falls onto concrete, paving or railings, which is relevant to which windows deserve attention first.
None of this makes any particular height safe. It explains why prevention focuses on the window rather than on what lies below it.
How restrictors are specified
Window restrictors limit the opening to a gap too narrow for a child to pass through while still allowing airflow. Building standards in many jurisdictions specify a maximum gap for this purpose.
Restrictors intended for homes with children include a release mechanism so the window can still be used as a fire escape, and that release is usually designed to require adult dexterity.
Requirements differ by country and by building type, and rented properties may have their own rules, so the specification that applies locally is worth checking rather than assuming.