Grounding the world’s commercial airliners in an attempt to stop the coronavirus crossing international borders could have an unexpected effect: weather forecasts may get less accurate.

That is because commercial planes often carry meteorological instruments, and the readings they gather feed into weather-forecasting models. With most flights cancelled , this valuable data set has been temporarily lost.

Stan Benjamin at the US National Oceanic and Atmospheric Administration says a similar situation occurred in 2010. That spring, the ash-laden eruption of Iceland’s Eyjafjallajökull volcano triggered Europe’s biggest shutdown …