End may 2014, is best time visit jiuzhaigou/huanglong? How is weather, rainly/lakes dried (no water)

It is ok to travel there then, but it is not the best season, which should be around Oct.

Well, in the end of May, it will be a little cool, with the lowest temp of 12-13C and the highest temp of around 24C. It can be a bit wet. Shower or light rain may happen now and then, so for your trip, simple rainy gear is needed.