Soft selection - surface test

[TubeSmokeGuy]

Make a box or else geo object. The particles initially have to be in the box' volume. Animate the box away from your wind source, so that your particles will leave the box' volume. Test the paricles with "surface test -> volume (outside)" and send them to the next event where your wind affects the particles.
Now your particles become smoothly affected by the wind. How smooth this transition would be depends on the speed of your box animation.