Research often assumes that, in rural areas of developing countries, adverse climatic conditions increase (climate driver mechanism) rather than reduce (climate inhibitor mechanism) migration, and that the impact of climate on migration is moderated by changes in agricultural productivity (agricultural pathway). Using representative census data in combination with high‐resolution climate data derived from the novel Terra Populus system, we explore the climate–migration relationship in rural Burkina Faso and Senegal. We construct four threshold‐based climate measures to investigate the effect of heatwaves, cold snaps, droughts, and excessive precipitation on the likelihood of household‐level international outmigration. Results from multilevel logit models show that excessive precipitation increases international migration from Senegal while heatwaves decrease international mobility in Burkina Faso, providing evidence for the climate inhibitor mechanism. Consistent with the agricultural pathway, interaction models and results from a geographically weighted regression reveal a conditional effect of droughts on international outmigration from Senegal, which becomes stronger in areas with high levels of groundnut production. Moreover, climate change effects show a clear seasonal pattern, with the strongest effects appearing when heatwaves overlap with the growing season and when excessive precipitation occurs prior to the growing season. Copyright © 2016 John Wiley & Sons, Ltd.