I found the poem that I was trying to remember. I recall my Gram reciting it to me when I was a kid -- she was often reciting poetry. That was just one of the things I loved about her.
Robert Herrick wrote this poem in the 1600's. It's supposed to be about youth and beauty fleeting, but I'm imagining it to be about summer fleeting, as well...
To the Virgins, to Make Much of Time
Gather ye rosebuds while ye may,
Old Time is still a-flying:
And this same flower that smiles to-day
To-morrow will be dying.
The glorious lamp of heaven, the sun,
The higher he's a-getting,
The sooner will his race be run,
And nearer he's to setting.
That age is best which is the first,
When youth and blood are warmer;
But being spent, the worse, and worst
Times still succeed the former.
Then be not coy, but use your time,
And while ye may, go marry:
For having lost but once your prime,
You may for ever tarry.
I don't really like that last stanza. I might write a rebuttal. What does a man know, anyway? Does Robert Herrick really think that I was in my prime when I was still sweet 16, or only until I got married? Hmph. It's a good poem, though.