October to December is the best travel time to Bhutan as the air is clean, bright, and fresh with the sunny blue sky. January and February are cold, but from April weather is dry and pleasant, and the famous rhododendrons bloom beautifully in late spring and fill the valleys with colour. Heat and humidity increase from May, and the rainy season from June to September cover the mountains. If you are interested in a rare black-necked crane, you should visit the Phobjikha Valley.