After Landfall
Wind speed usually decreases significantly within 12 hours of landfall (see the graph below). This is partly because the roughness of the terrain increases friction, slowing the air. Also, once the storm is over land, it is usually cut off from the heat and moisture sources that sustain it. Note that, after about 24 hours after landfall, the wind impacts from a tropical storm can be similar to those from a hurricane.
Wind gusts (as opposed to the sustained winds shown in the graph) may actually increase after landfall because there is more turbulence over land, which mixes faster air to the surface in short bursts. Note too that winds can stay above hurricane strength well inland. For example, Hurricane Hugo (1989) battered Charlotte, North Carolina, which is 175 miles (280 km) inland, with gusts to nearly 100 mph (90 kt). Hurricane Ike (2008) became an extratropical cyclone with hurricane-force winds after it moved well inland, causing widespread damage across the Ohio Valley and lower Great Lakes and on into Ontario.