Hi

You are definitely going to need to be more specific here to get a sensible answer. You are right, India is a huge place with a wide variety of climates, but I will have a crack for you anyway.

Just for reference, I have ridden in both the North a bit and (a great deal more as I go there for work a few times a year) in the South. I should also say I have not been to the far North (Kashmir / Jammu etc.) so have no reference for the more mountainous areas.

In the South (Bangalore on down) it is baking hot in July / August and yep, you will get rained on. The pattern though in my experience is all over the place. Sometimes it will be like SE Asia where it builds up during the day and unloads in the afternoon...but other times it won't rain at all...changes daily. Then you ride out of the plains and over the Western Ghats through the tiger reserves and tea plantations (mountains to the west) and it's bucketing down constantly. Ride over the Eastern Ghats (smaller mountains to the east) and it's dry and dusty and sweltering. These are all only a few hundred ks or so apart from each other. So it's all over the place really.

For example, this year (2018) they had massive flooding in the South, the year or so before...riots over water shortages as the rains didn't come. So it's really hard to pinpoint.

You can expect to be hot as hell either way though.

The North (Delhi, Agra through to Rajastan) is going to also be hot and dusty, but rain will be less of an issue. It's much much dryer especially (and obviously) in the desert areas. Into the mountains (Udaipur etc.) you can get a lot of rain that time of year but again there is nothing regular about it at all and water shortages are becoming increasingly an issue. Good news is in July/August the smog in Delhi drops a little to below "instadeath" levels (January & June are to be avoided if you value your lungs).

So..really when it comes to riding in India, rain makes no difference either way as it doesn't help or really hinder much. It will be hot, it might be wet and the traffic will be bonkers regardless and you will have an absolute ball.

Good Luck!

Cheers
John