Abstract The purpose of the present research was to determine the relationship of IQ to precipitation and other climatic variables in 128 countries of Africa, Asia, and Europe. Lower precipitation, temperature, and nasal index were associated with higher IQ. Temperature range and humidity were positively associated with IQ as predicted by evolutionary theory. Additionally, discriminant function analyses showed that the variables that best discriminated between the groups of countries were IQ, temperature, precipitation, humidity, and nasal index. The discriminant functions correctly classified over 90% of the cases. Precipitation, temperature, and nasal index were contributors to multiple regression with IQ as the dependent variable.