Summer, like all the seasons, has a distinct set of scents that are associated with it.  Smell is, it seems to me, an underappreciated sense, perhaps because of that it is often an extremely powerful trigger for the mind.  In any case, here in southern New England summertime is associated primarily with hot pine/tar and cut grass.  Other scents can be incredibly specific: oriental lilies outside a window at dusk or the sharp herbal bouquet from weeding an herb garden: sage, mint, thyme, chamomile.  The swamp forest’s mix of decay and growth, a hayfield’s sweet, dry scent, or phlox’s delicate floral scent.