hey that's so cool. i was recently asked about opening your windows before a tornado to equalize the pressure between the outside. YouTube·CBS Pittsburgh
Some people believe that opening windows on the side of the house facing the tornado will help equalize the air pressure inside and outside the home, reducing the likelihood of the roof being blown off. However, this theory has been largely debunked.
An Analysis of Residential Safety Protocols: Evaluating the "Open Window" Myth vs. Modern Structural Engineering Recommendations for Tornado Events
While it is true that a tornado’s central pressure can be 100–200 millibars lower than ambient pressure (e.g., a drop from 1013 mb to 850 mb), this change does not occur instantly. The pressure drop happens over several seconds to minutes as the tornado approaches and passes. A typical residential structure is not airtight; it has leaks around doors, windows, attics, and vents. These natural leaks allow for relatively rapid pressure equalization without the need to open a window.
The preponderance of evidence from meteorological science, structural engineering, and empirical disaster research concludes that . There is no measurable safety benefit, and the practice significantly increases the risk of structural collapse, debris injury, and death.
Does opening windows and doors actually do anything in a tornado? : r/tornado
The primary destructive force of a tornado is not pressure, but .
| Factor | Windows | Windows Closed | | :--- | :--- | :--- | | Pressure Equalization | Minimal benefit; natural leakage already achieves this. | Sufficient; no dangerous differential accumulates. | | Internal Wind Speed | High-speed inflow creates internal vortex, lifting roof. | Zero internal wind from exterior. | | Debris Entry | Direct, unimpeded pathway for lethal missiles. | Blocked; glass may break but slows debris velocity. | | Structural Integrity | Severely compromised; internal pressurization aids collapse. | Maintained; wind flows around the envelope. | | Time Efficiency | Wastes 30–60 seconds hunting for windows. | Allows immediate sheltering. | | Risk of Injury | High (cuts from opening, debris entry, glass blow-back). | Low (broken glass stays mostly near window frame). |
Opening a window creates a direct pathway for high-velocity debris (2x4 planks, roofing shingles, broken glass, lawn furniture) to enter the living space. These missiles are the leading cause of injury and death during tornadoes, not pressure effects.