I doubt the weather has anything to do with it. Rain fade due to thunderstorms is common, especially for Ku Band (less so for C band). India is known for being Monsoon central. The weather causes signals to degrade, it has no effect on the encryption system. If it did, I can assure you my wife would be outside hosing the dish
The only reason why channels appear which you have not paid for is because the provider turns the encryption off. No other reason.
They do this occasionally for testing and they do it occasionally for promotional reasons. If you can occasionally see what is on other channels, you may subscribe to them.
That's the logic. A service provider might put a first episode first season free to air to suck people in to subscribing to that channel.
The reason why some other services even your neighbour may not get the same service unencrypted for a short period of time is because subscribers are in groups.
Certain keys are common to certain groups, users, channels and areas. The provider can divide up their customers in a number of different ways.
If you're a person who watches sports, you may subscribe to one of two sports packages. So every now and then, I'm going to un-encrypt the channels from the premium group so that those on the cheaper package can see them. I know they like sports and if they like what they see, they might upgrade.
Or, when it's not sports season, I might think you're wife is sitting down at the end of the day. I might open up a few drama channels in the hope that she might see them and nag you to subscribe to them.
Of course if it's raining outside, chances are you're sitting down inside watching TV. What better time to influence your behaviour via TV