First of all Don't snowboard in June the snow is terrible, you'll be disappointed and significantly poorer. If you can't make other arrangements and really, really, really, really, want to snowboard on wet horrible snow then you'll have to go to either Banff or Jasper as these are the only two hills which will have any snow whatsoever along with a slight possibility of fresh pow in the summer time, though it is very unlikely. There is a Glacier on Whistler but, I don't recommend it so late in the year. The only other places which may have snow are up in the far North of British Columbia or the Yukon but both areas are difficult to get to.