We are going to be blunt, because this is the one question where a wrong answer gets people hurt: monsoon in the Uttarakhand mountains carries real risk. Here is the honest guide.
July-August brings heavy rain to the Himalaya, and the consequences are not cosmetic:
Most operators will happily sell you a monsoon Char Dham. We generally advise against it, and we would rather lose the booking than put you on that road.
The Valley of Flowers. This UNESCO World Heritage site only blooms in monsoon — roughly July to early September — when over 500 species carpet the valley. It does not exist at any other time of year.
If this is your goal, go. But go properly: buffer days, insurance, a good operator, and full acceptance that the schedule may break. Hemkund Sahib shares the same base and season.
Risk is not uniform. Lower-altitude, non-mountain-road destinations fare far better:
We build monsoon itineraries with real buffers, and we will tell you honestly when the answer should be 'go in September instead'.