I'm near Portland, OR and we a similar short summer that you did. I'm sorry your onions didn't finish up earlier but all is not lost.
You said the onions are good sized so go ahead and start eating them. Because the tops didn't fall and the onions haven't formed a skin they won't be the best keepers but you can still be eating them for a month or so.
If the necks are softening and you have a lot of onions, then you can pull em and cure in a dry place. Maybe they will last longer than a few months.
Good luck.