Netro supports Dark Sky, AccuWeather, OpenWeatherMap and WeatherUnderground. We suggest you visit the official website to check the historical data to choose the most accurate one.
Netro tries the best to provide accurate watering schedule even with incorrect forecast. First, we periodically update the weather data, once the weather data is changed, we update the un-executed schedules ASAP. Second, we re-check the weather data for the past, update our model, and adjust following schedules accordingly. For example, Netro may not water today due to large rainfall from forecast data. The next day, Netro re-check the weather data, if no rainfall found and your soil is dry enough, Netro will water accordingly.