There are many things in play here. Warm summer nights might mean that your speakers and electronics too are operating differently...your electricity and any other permutation could change the sound.
turntable sounds better on warm summer nights
On warm summer evenings it has more presence than cooler winter evenings.I presume this has something to do with the tracking weight of my clearaudio virtuoso wood MM cartridge on warm evenings when the room gets to about 75. If it sounds better in the summer do I add or subtract weight in the winter when the room is about 5 degrees F cooler, in order to get the same summer sound?