A sudden gust turns a familiar object into a lever. The fabric catches moving air, and the frame has to carry that load back to your hand. Understanding that load is more useful than relying on the word “windproof”.
Wind speed is only part of the story
The standard drag equation includes air density, exposed area, shape and the square of air speed. If the other terms stay constant, doubling the speed produces four times the drag. An umbrella changes shape and angle in a gust, so that simple relationship is an illustration, not a performance rating.
Follow the load
Air acts on the canopy. The fabric transfers force to the ribs, which connect through the frame to the shaft and handle. Connections matter as much as the names of the materials. An intact rib does not help if a joint or attachment fails.
What does a wind test tell you?
A meaningful claim needs conditions: the exact model tested, its orientation, the air speed and whether the test checked inversion, breakage or operation afterwards. A single number without that context is incomplete.
For everyday use
Follow the instructions for your model. If conditions make the umbrella difficult to control, close it when safe and take shelter. Never treat an umbrella as protection from dangerous weather.
This is a general construction guide, not a certified wind rating for HARDBRELLA.
Reference: NASA — The drag equation.