In comparison with the reference group of normal rainfall, two or more than two months’ excess rainfall during the wet season increases significantly the incidence of diarrhea (p= 5.0), while one month of excess rainfall does not significantly affect diarrheal incidence. In our random effects models on average, excess rainfall increases the incidence of diarrhea by about 2.1 percentage points in the model without country fixed effects and by 2.6 percentage points in a model with country fixed effects. This is a notable increase given the sample mean of diarrheal incidence is 22.5 percent. This finding is consistent with the existing evidence that shows that there is a strong association between heavy rainfall and outbreaks of diarrhea caused by waterborne disease (Curreiro et al., 2001).

The results also show that prolonged excess rainfall (two months or more) increases the proportion of weight-for-height malnutrition among children under three years of age by 1.7 percentage points (Table 4). But this effect does not persist in the full model (Table A). There is also tentative evidence on the link between heavy rainfall and height-for-age malnutrition: the coefficient is significant in the OLS specification but not in the random effects model (Table A). Thus the impact of sustained above average rainfall is to raise short-term malnutrition rates and possibly that of long-term malnutrition.

Another crucial finding of this study is the statistically significant impact of maximum and minimum temperature on the incidence of diarrhea and weight-for-height malnutrition. These results are robust and significant in our random effects specifications for both diarrhea and weight for height malnutrition, and also persist in the full model (Table A). The results in Table 4 show that an increase in monthly minimum temperature reduces diarrheal incidence within a region by 0.45 percentage points. A 1.0 degree Celsius increase in monthly maximum temperature increases the incidence of diarrhea by about 0.6 percentage points and increases the proportion of the population affected by weight for height malnutrition by 0.3 percentage points in the parsimonious specification. The estimated impact on weight for height malnutrition is important, representing in the region of a 3 percent increase in the incidence given that the average prevalence of weight for height malnutrition is 9 percent.

Our findings on the impact of temperature on diarrheal incidence are in line with two studies in the developing country context which focus on the statistical association between temperature and diarrheal incidence. Using data on daily number of hospital admissions of children under ten years of age with diarrhea in Lima, Peru, Checkley et al. (2000) showed diarrheal admissions increase 8 percent for every one degree Celsius increase in temperature (average across all seasons). Singh et al. (2001), using monthly data for Fiji, provided an estimate of about 3 percent increase in diarrheal notification for a one degree Celsius increase in temperature.

Our measure of diarrhea is not directly comparable with these estimates as the focus of these studies is hospital admissions whereas our measure relates to households’ reporting of diarrhea. A further study that controls for access to water and sanitation and socioeconomic status in Dakha, Bangladesh, found that the percentage change in the 12