We examine how Syria’s local growing seasons and precipitation variability affected patterns of violence during the country’s civil war (2011–19). Among Syria’s 272 subdistricts (nahiyah), we study conflict events initiated by the Assad regime or its allies, and, separately, by other armed non-government groups (‘rebels’). Throughout the war, violence to capture agriculture has been used regularly to control valuable cropland and harvests. Combatants also seek to deny their adversaries access to these resources by deploying violence to destroy agriculture. We test the hypothesis that conflict was most likely during local growing seasons due to both of these motivations. Additionally, we examine whether unusually dry conditions further elevated the risk of conflict during growing season months. A theory for why higher levels of conflict would occur during unusually dry conditions is that livelihood losses elevate incentives to control scarce crops and also facilitate recruitment of militants or their sympathizers. We find that violent events initiated by the government and rebel groups are both more likely during the growing season than other times of the year. There is also evidence that dry conditions during the growing season led to an increase in government-initiated attacks over the duration of the war. We find the strongest relationship between precipitation deficits and both government- and rebel-initiated violence in later years of the war. Compared with our growing season results, the rainfall deviation estimates are less consistent across models.