The most popular drink in the world is tea, and ideal conditions for  tea cultivation are temperatures between 21°C to 29°C, rainfall of 150-250cm with no stagnation of water, and humus rich soil mixed with lime and iron. In this article, the effect of seasonality and amount of rainfall on tea production in Sri Lanka is investigated via the time series method of autoregressive integrated moving average modeling with predictors (ARMAX); the monthly data for this study is collected from eight tea estates in Sri Lanka, over the years 2009-2017. Our results indicate that, with one exception, rainfall does not significantly affect tea production, possibly due to each tea estate receiving rainfall that is sufficient for tea production. Our results also show that a total of six out of the eight tea estates exhibit increasing trend during the study period.

tea estate, seasonal, time series, ARMAX, rainfall.