How to use "summers ago"

Solution 1:

My intuition is that "last summer" is the summer most recently completed, and "two summers ago" is the summer before that, so you'd say "three summers ago". But if there is a chance for confusion, better say the year to be sure.

Solution 2:

I'd say "two summers ago", but I think it's inherently ambiguous. If you want to be clear, you could say "the summer of 2009".

Sometimes people say "two years ago this past August" or "three years ago next August". But to me this starts to sound more like a riddle that needs to be solved than a clear statement of time.

Solution 3:

In summer 2011, "two summers ago" refers clearly to summer 2009, but sometime in late fall to early winter it becomes ambiguous whether summer 2009 or 2010 is meant.

For clarity, I'd use "summer two years ago".