This is a question from Alejandro Reyes = "I have a question about protecting transmitter and lavalier mics in rain what's the best method for this?"
There are several ways that I have heard of and tested some:
You can completely cover and actually make completely water proof with AquaPacks but obviously when underwater the RF doesn't work underwater.
You can also use UNLUBRICATED condoms and then tie them off at the wire to give them a rubber coating to make it waterprrof and then all you have to worry about is how you tie it off to not let moisture in. This also works for when it is very hot and actors are sweaty.
Another option is to cover them in a small plastic bag but make sure you then hold them in a soft pouch to stop any rustling and there are several manufacturers with pouches and waist belts to help you acheive this.
You can turn lavs unside down so the grill of the microphone points down and then you reduce the risk of water running into the grill.
You can also get a lav with such a small capsule that most water is repelled off it like a Countryman B3 or B6.
There is more in the video but let me know what you think down in the comments.