Suitable Climate
The most suitable condition for growing tea is around 55 degrees Fahrenheit with 60 inches of rain annually. Especially during the months between April and October, 40 inches of rain on average are needed. In addition, a nice amount of sunny days gives the tea extra good quality. Tea grown in high altitude regions makes for high quality. Farms on flat lands produce medium quality tea with lower costs.
An Experiment done in Assam, India found that higher rainfall during the months of January through March and warmer temperatures led to be the most beneficial to the tea crop.
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0109126
