Could you please tell me the meaning of "hot" in the following excerpt of the chapter 7 of The Great Gatsby by F. Scott Fitzgerald? Does he employ it in a metaphoric sense?
The next day was broiling, almost the last, certainly the warmest, of the summer. As my train emerged from the tunnel into sunlight, only the hot whistles of the National Biscuit Company broke the simmering hush at noon.
Fitzgerald is using imagery to help his reader create a mental image of the world he is describing. He describes the heat and the way that things look in the heat. The "shimmering" effect can often be seen on a hot day. Things appear to glisten and shine like the surface of water. Everything seems to sag and hiss in the heat of the midday summer sun. Even the whistle Fitzgerald describes as hot because it's sound and appearance would seem to be steamy on such a day. Perhaps the whistle sounds tired or out of breath. Fitzgerald tells us the whistle sounds hot. This use of imagery and personification allow the reader to connect with the passage. The meaning of the word "hot" is therefore defined by the individual reader.