What would be the age group of the target audience for this story?

I agree with pohnpei that this Ray Bradbury short story is
one that should appeal to all ages. The themes of the story, concerning the nuclear
destruction of life on Earth, is certainly pertinent to all humans--especially at the
time it was written, 1950, just five years after the atomic bombs were dropped over
Japan. I have taught this story in high school (a combined 9th-10th grade science
fiction class), and I believe the text in which it was included was from that
approximate age group. The title was borrowed from a 19th century poem by Sara
Teasdale.