Thank you for your question. It is difficult to recall from year to year when they dropped, and this OSU article (http://owic.oregonstate.edu/bigleaf-maple-acer-macrophyllum) indicates that: "Bigleaf maple seeds are borne in pubescent, double samaras with wings from 1.4 to 2 in. long. Seeds are triangular or oval in shape and 0.16 to 0.47 in. long. There are from 2700 to 4000 seeds/lb. Seeds ripen early in September and October, and are dispersed by the wind from October through January. Many seeds may remain on trees during this period."  I suspect the period varies from year to year, depending upon amount of precipitation and temperatures.  So, relax.  Take a few more weeks before you have to start sweeping!

Kristena 

Thank you very much.  I thought seed dispersal was a springtime occurrence.  They should start dropping soon.

It takes all spring and then summer for the plants to create flowers and seeds, and then they’re ready to go their own way. You’re probly recalling the pollen and petals!

Probably so.  Again, thank you for your and quick response.  I appreciate it.

You’re welcome!