900 Signal Drops When Temperature Is Above Freezing?

We have a heavily wooded area which is served with a directional 900 AP. A customer there has noticed that when the temperature is below freezing, his signal improves by 15-20 dBm. He’s got a connectorized 900 SM with a grid dish. We’ve confirmed that all his connections are bone dry. Is the foliage affecting the signal differently when it’s frozen, or might it be something else?

Wow, that’s really interesting. I know that water and metal don’t mesh well with RF signals, but I assumed ice would have the same affect. Apparently not in this case.