Why does the documentation say this field returns the intensity of precipitation in UnitSpeed, this seems confusing. Shouldn't the amount of precipitation be an amount like inch/hr, mm/hr why would the value be in speed?
The old dark sky documentation for this field shows the units were returned in inches/hour
The units of inches/hour (distance divided by time) is a speed. The only difference with WeatherKit is that it uses km/hr instead of in/hr — it's is the same information at a different scale factor. Since precipitationIntensity is a Measurement, you can easily convert it to other units if you want.
I don't think Apple uses kph for precipitation intensity, at least not currently / anymore. I ran a 240h hourly API request and the precipitation amount ranges from 0 to 1.9. The precipitation intensity is identical to the precipitation amount. Since it's hourly granularity, the unit of speed is definitely not "per second" so not m/s. also K/h is implausible because 1.9 kph = 75000 inches per hour.
I would venture to guess that precipitation is "cm" and precipitation intensity is "cm/h"
Has anyone found explicit confirmation of the units? I don't see it anywhere in Apple's documentation.
cloudCover: % daylight: T/F humidity: % precipitationAmount: cm ? precipitationIntensity: cm/h ? precipitationChance:% pressure: hPa ? snowfallIntensity: cm/h snowfallAmount: cm temperature: C temperatureApparent: C temperatureDewPoint: C uvIndex: 0-10? visibility: m? windDirection: degrees ? windGust: m/s ? windSpeed: m/s ?