For trees to be uprooted or knocked down by wind the wind needs to be at least 55 MPH and blowing constantly.
Wind needs to be blowing constantly at 55 MPH to 63 MPH or above to uproot trees and blow them down.
Also at 55 MPH to 63 MPH wind gusts not only can trees be knocked down but also damage to buildings, roofs, etc can be done.
If there is gonna be wind blowing or a storm coming through you should make sure you put away anything that can blow around such as patio chairs, trash cans etc.
That way they will not blow into other peoples yards or do damage to other peoples property or your own property.