Yield of tea is greatly influenced by climatic conditions especially rainfall and temperature. Scanty rainfall causes severe losses and heavy rainfall result in soil erosion and wash away of fertilizers. Highest tea production is seen at 4000 mm to 4600 mm. The temperature and humidity had no direct effect on tea leaf production. It depends on solar radiation and soil quality. If there is a cool season, with average temperatures 20 °F (11 °C) or more below those of the warm season, the growth rate will decrease.