We were on Maui from mid July to mid August, and only 1 day did the Seaglass Gods smile on us at Cheeseburger beach (Front St.)
That is not to say we didn't have good luck during our trip....we did. We found some of the best pieces yet including a HUGE thick amber in the shape of an "L" (for Lahaina) that a couple of the sea glass artists (hi Creighton) wanted.
If the tide is right and the sand is stripped away you will find lots of old color on Front St beach.