"Heat" is a short and dense poem and it's frickin' awesome to listen to. When you read it silently to yourself, you might miss out on the poem's subtle repetitions, so be sure to read it out loud. Better yet, get yourself a nice cool glass of lemonade, sit back, relax, and ask a pal to read "Heat" to you.
This way, you'll hear all of the poem's refined repetitions. There's alliteration all over this poem ("points of pears"). There's consonance (check out the repeated T sound in "cut apart the heat"). There are repeated words ("rend" and "heat" in the first stanza).
All of these repeated words and sounds make the poem feel like a little cocoon of heat. Do you feel all warm and snuggly? Or do you, like the speaker, feel claustrophobic as your temperature rises? Either way, the sound of this poem is to blame (or to thank!).