Better sound on rainy days?

As posted, completely explicable over FM by atmospheric conditions.

Not explicable for other local media generated programme.  If you hear improvement then I suggest you install a shower in your listening room.

The rest of us can just enjoy the music.

My favorite radio station is WBGO FM. Jazz Station is in Newark, NJ, but broadcasting antenna is in NYC 26 miles away.

My 2012 Volvo C70's miserable radio can only receive a strong enough signal to be noise free on cloudy days.

Comes in fine in everybody else's car every day all day.

Just a bit more signal please.

I am going to install a fire sprinkler system in my listening room and keep it on when listening to FM on my tuner.

FM tuner reception is clearly better on cloudy days. I have not noted any equivalent weather difference when live-streaming the same signal (often, in various weathers, I A/B the two, analog vs. digital). The "atmospheric conditions" explanation has always seemed true to me. 

Temperatire yes, air pressure and then ionization...

Ionization play a role very important because it affect the body too and not only the diffusion of the waves...