The effects of soil drought, air temperature, sunshine and relative humidity on flowering and fruit production in cassava (cv. CE-165) were studied in Thiruvananthapuram, Kerala, India, under field conditions for a period of 21 months (July 2003 to March 2005). Adequate soil moisture promoted flowering and fruit production, while soil drought suppressed these parameters. High air temperatures (>30°C) and low relative humidity appeared to aggravate the adverse effect of soil drought on flower and fruit production. It was concluded that under tropical field conditions, soil moisture is the critical factor which influences flower and fruit production in cassava, and high air temperature (>30°C) and low relative humidity aggravate the adverse effect of soil drought.