John, at your distance there are a few reasons.

#1 - Warmer weather is increasing so the ionosphere is shifting and not conducive for longer distance (non local) listening.

#2 - Massive noise from all the storms the US (not just local) have been experiencing.

#3 - When the AC goes on, along with fans and other "warmer" time stuff, you will notice more noise or lower Am signals.

If it was massively dry, it affects ground conductivity.. That DEF is not an issue for us recently!

Just curious John. Do you use a vertical antenna or horizontal wire or both?

Z