How do inputs and weather drive wheat yield volatility? The example of Germany

•Decomposes wheat yield volatility in input- and weather-driven categories.•Rich data set with inputs, weather and phenology.•Relating yield and weather offers valid approximations for climate impact research.

Increases in cereals production risk are commonly related to increases in weather risk. We analyze weather-induced changes in wheat yield volatility as a systemic weather risk in Germany. We disentangle, however, the relative impacts of inputs and weather on regional yield volatility. For this purpose we augment a production function with phenologically aggregated weather variables. Increasing volatility can be traced back to weather changes only in some regions. On average, inputs explain 49% of the total actual wheat yield volatility, while weather explains 43%. Models with only weather variables deliver biased but reasonable approximations for climate impact research.