We all worry so much about receiver sensitivity, transmitter power or field strength, and often forget about how much the lowly weather can have an impact on listenable range for FM (and even AM) signals.
The last few days have been very foggy here in the Pacific Northwest. I was out driving and listening to Artisan Radio, and noted that the listenable range during these conditions is considerably more. On the order of 1/3 to 1/2 more than usual. Most of the improvement was in the fringe listening area - the solid strength range improved, but not all that much.
That makes sense, since most of a Part 15's FM listening area is fringe, and even adding a uv or 2 through whatever mechanism is being observed would make a huge difference to sensitive car receivers.
Yes it does...I was out yesterday. I was able to hear my AM 1700 3.5 miles away to the south, which usually tops out at 1-1.5 miles. It was a cold around 20F, cloudy day with snow showers around. My normal radius is up to 2 miles. But yesterday range nearly doubled.
@wefr My signal is much stronger when it's cold and during the Winter. It doesn't seem to go much further but the strong signal zone moves out and extra mile . Medium wave is a Winter band .