Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
It’s probably remants from his hardcore science fiction days, but Bradbury shows a clear flair for intensity here. Characters are extreme rather than realistic (Clarisse is the kooky yet wise outsider, Beatty the secretly intellectual, moustache-donning-villain, Mildred the vacant wife, Faber the reluctantly rebellious ex-professor, etc.). Events are apocalyptic (big fires, lots of bombs), and confrontations exist only on the grandest of scales (cars swerving to hit pedestrians, the occasional flame-thrower murder).