The best time to visit Patan — and the Kathmandu Valley generally — is during the dry seasons: October to November and March to April. Skies are clear, temperatures are comfortable (15–25°C), and the mountains are visible from high ground. The monsoon runs from June to September; rain falls heavily in the afternoons, streets flood, and the valley turns intensely green. Winter (December to February) is dry but cold, especially at night.
Rato Machhindranath Chariot Festival (April–May) is Patan's most spectacular event. A massive wooden chariot, built fresh each year, is hauled through the city's streets over several weeks by teams of rope-pullers. The festival honours the god of rain and harvest and has been observed here for centuries. The final ceremony — displaying the jewelled vest of the god — only takes place when astrologers declare the time auspicious, and may happen only once every decade or so.
Janai Purnima (August full moon) brings large crowds to Kumbheshwar Temple, where pilgrims bathe in the sacred pond. Krishna Janmashtami (August–September) is observed at the Krishna Mandir in Durbar Square with all-night prayers and oil lamps illuminating the stone frieze.