Since we were just talking about this-- from Sat DRF, emphasis added by me:
\"Man, there was a headwind\", exercise rider Bobin Smullen said. \"I had to get a little lower to see if I could get out of it. AROUND THE TURN I FELT NOTHING; TURNING DOWN THE LANE I ALMOST GOT BLOWN OFF THE HORSE.\"
So either the wind picked up dramatically during the work (read race), or, more likely, the grandstand was blocking it at some parts of the track. Either way it goes to show that wind readings, even taken by live obvservers looking at flags, ripples on infield lakes, etc., before and after races, can be greatly innacurate (that was an extreme wind Robin was talking about, one that could easily have a 2-3 point effect on time). Wind readings from airports, which another service used proudly for decades and may still use, are taken periodically (hourly), several miles from the track, and are worthless.
Ultimately wind observations, like ground and track maintenance, are info bits you use. But you make your figures using the figure histories of the horses, and the more you do it the tighter your data base gets, making the figures you then make using it even more accurate with time.