The best time for a week-long trip to Bhutan is generally during the spring (March to May) or autumn (September to November). These seasons offer the most pleasant weather with clear skies, mild temperatures, and vibrant landscapes, ideal for sightseeing, trekking, and experiencing Bhutan's culture.

Here's a more detailed breakdown:

Spring (March to May):

• Weather: Pleasant and mild, with temperatures ranging from 8°C to 24°C (46.4°F to 75.2°F). Expect mostly dry conditions and clear blue skies, although occasional short showers are possible, especially in May.
• Scenery: Valleys come alive with blooming flowers, including rhododendrons (peak bloom from late April to May). Landscapes are lush and green.
• Activities: Excellent for outdoor activities like trekking, hiking, rafting, and birdwatching.
• Festivals: Several colorful Tshechus (festivals) occur in spring, such as Punakha Drubchen and Tshechu in March, Talo Tshechu, Gom Kora, Zhemgang Tshechu, Gasa Tshechu, and the famous Paro Tshechu in April, and Domkhar Tshechu and Ura Yakchoe in May. The Rhododendron Festival in Thimphu also takes place in April.
• Crowds & Costs: Peak tourist season, expect more visitors and higher prices. Booking in advance is recommended.

Autumn (September to November):

• Weather: Sunny days, clear blue skies, and crisp, cool air. Temperatures range from 7°C to 25°C (44.6°F to 77°F). Minimal rainfall and low humidity offer excellent visibility of the Himalayas.
• Scenery: Stunning landscapes with golden hues of ripening rice fields and autumnal colors on the hills.
• Activities: Another prime time for trekking and outdoor adventures with magnificent views. Popular for cultural tours and sightseeing.
• Festivals: Several significant festivals take place in autumn, including Thimphu Drubchen in September, Wangdue Tshechu and Thimphu Tshechu in October, Gangtey Tshechu, Jambay Lhakhang Drup, Prakhar Duchhoed, and the Black-Necked Crane Festival in November.
• Crowds & Costs: Peak tourist season, similar to spring, with higher prices and more visitors. Early booking is essential.

Other times to consider (with potential drawbacks):

• Summer (June to August): Monsoon season with frequent showers, lush green landscapes, fewer tourists, and some summer festivals in less-visited areas like the Haa Valley in July.
• Winter (December to February): Cold with potential sub-freezing temperatures, especially at higher altitudes. Snowfall can block high mountain passes. Clear skies offer great views of snow-capped mountains, fewer tourists, and potentially lower accommodation rates. The Black-Necked Crane Festival can be seen in Phobjikha Valley until mid-February, and festivals like Trongsa Tshechu and Nalakhar Tshechu occur in December, with Punakha Drubchen sometimes extending into early March.

Considering your preference for weather, activities, and festivals, spring (March-May) and autumn (September-November) are the best times for a week-long trip to Bhutan. To align your trip with specific interests like attending a particular festival or seeing the rhododendron blooms, check the festival calendar for 2025. Remember that festival dates can sometimes shift based on the lunar calendar.