The ideal time to visit the region is during October when the temperature starts to cool down. The worst time to visit the area is during the summer which is from March until June and because of the heat the trek should be avoided. However, it is possible if you make sure you are properly equipped.
The worst time to trek the area is from June until September which is the monsoon season and the heavy rains will make trekking in the area impossible and extremely hard. However, you can come during the winter, which is from October until March, but be aware of the cooler temperatures and dress appropriately.