Winds aloft

The winds on the surface are just one of our concerns. We have to think three dimensionally and consider what the wind is doing at altitude as well. This is perhaps the most confusing aspect for our passengers. There is not even a hint of a breeze on the ground and your flight has just been cancelled due to wind, how come? We look at winds at the surface (the wind you can feel) and the winds at 1 to 9,000 feet. We are not going to 9,000 feet, but it tells us if we might encounter issues such as wind shear, turbulence, or strong surface winds later on. Even if there are no winds to speak of at the surface, the winds aloft may drive our decision not to fly. Winds aloft of 18 20 knots or 20 miles per hour can be sufficient to reschedule a flight.