Abstract
Water usage in Mecca is dominated by trends and cyclical variations in the number of foreign pilgrims visiting for the annual Hajj Pilgrimage. Time series regressions show that the mean temperature in Mecca at the time of the Hajj affects the number of pilgrims, inducing a long-term cyclical pattern for this variable and therefore water usage. The cointegrating relation between water usage, number of external pilgrims and temperature produces long-run forecasts of Mecca water demand.