Here’s a monthly breakup of GANGTOK's climatic conditions so you can plan when to go:
During Spring: Best time to visit any hill station is certainly during spring. Gangtok is famous for Rhododendron flowers. They bloom their best during the spring season. Spring lasts from March to June. this is the best possible time of the year when you can actually enjoy flowers everywhere in the valley. The valley looks drop dead gorgeous with all the flowers bloomed everywhere. You can also visit this place in the late autumn months. From the month of september, the autumn starts. You will get to see some wonderful waterfalls and beautiful picturesque places everywhere. Sikkim is a state where you will get viewpoints everywhere. Any place you get down from your car and you will get breathtakingly beautiful locales around you. During Rainy season: Rainy season is a strict no no thing for travellers. Lots of people travel to Gangtok by bike. Traveling to Gangtok during rainy season is not recommended due to safety purposes. Being a hilly area, incidents of landslides and road blockage are common during heavy rainfall. Even with experienced drivers and four wheelers, travelling to Gangtok during Rainy season is not recommended.