The iPhone is very susceptible to wind, even a moderate breeze.
The problem is, while it’s difficult to hear when you playback your audio on your iPhone, wind gets magnified by a radio or TV station’s audio processing chain, and the listener hears a very distorted sound.
For 3 bucks, buy a regular microphone windscreen from Amazon.
Here’s the workaround:
Rather than standing outside to record your track or natural sound, sit in your car and open all or some of your windows.
Turn your head to the left (or right if you’re in England) and read out your window.
The car will block the wind, but will allow the natural sound in.
Let me know if you have any questions.