In this latest update, Google has adjusted this to allow for more granularity. Newly added “Temperature” and “Weather units” sections in Pixel Weather’s settings menu allow for changes for each unit of measurement. These include: Precipitation, Wind Speed, Barometric Pressure, Visibility

I’m from the US, but I usually switch units to metric as much as possible. Currently, I can only switch over the temperature. It’ll be great to switch over the rest of the data. Great news!