I and my partner did Upper Mustang Trek with Himalayanleisure in June 2018. It was a great experience. The flights couldn't happen due to bad weather so we took a private jeep which was an adventure. The trek was arranged nicely and the staffs were very caring. Our guide and porter made the trek possible. It is a beautiful trek I can recommend to other people in rainy season in Nepal. In general, when we reach high, there was no rain.