Three short lines, and the whole poem rests on one odd contradiction: the sun has gone, yet the warmth hasn't. We expect heat to vanish when its source does, so the speaker's observation feels a little unsettling, like noticing something that shouldn't quite be true.
The poem never says what the heat is, and that's what makes it interesting. Literally, it could be the evening air, still warm after a hot day, or a day hidden behind clouds. But the wording invites a wider reading. The heat might be a feeling, a memory, a tension, or the lingering presence of someone or something that has already left. The speaker doesn't explain or complain. The tone is quiet and observant, even a bit weary.
The mood is close and sticky, a sense of being unable to cool down or move on. The dash and the line breaks slow the poem down, so the last line, "the heat is still around," seems to hang in the air, just as the heat does.