And what do you think "weather" is ? Let me help by quoting wiki: "Weather is the state of the atmosphere".
The word
stateis the most important one in there.
GPS is a receiver. There is no communication in the other direction whatsoever, its a passive device, just like an FM radio.
While GPS is indeed a receiver, in it basic for it is passive, since it was built for the army in a way that when you are in an enemy territory you don't emit a signal and thus you can't be detected, but today there are variants that are Active, not to mention the complementary services that are there track and sent those data back, If I'm not mistaking modern planes are equiped with such device, but I'm not so sure