Weather conditions are an important determinant of agricultural factor input, particularly labor allocation. The availability of weather forecasts can therefore lead to efficiency gains in the form of cost decreases and productivity increases. We test the practical feasibility, the uptake, and the effect of providing basic weather forecasts in the rainy season on the labor productivity of smallholder farmers. For this purpose, we conducted a Randomized Controlled Trial as a pilot with monthly data collections involving 331 farmers across six villages in northern Benin. We find that most farmers subscribe to the intervention and report satisfaction with the service. The impact estimates indicate positive and economically significant intention-to-treat and local average treatment effects in terms of reduced relative labor costs, increased yield and, in turn, increased labor productivity for maize and cotton cultivation. These benefits come at relatively low cost, suggesting that weather-related information via mobile phone outreach holds promise for helping smallholder farmers to better adapt to changing weather.