Beside temperature and humidity, a key data is the rainfall amount, which is also almost the most challenging data to predicate for weather providers. Two weather providers (AccuWeather & Darksky) provide different rain amount. For example, on 08/28, AccuWeather data is 3.5m(~0.14inch), and Darksky data is 20mm(0.8inch). Even on sunny days, their value are not identical. e.g. on 08/22, AccuWeather is 0, but Darksky is 1.3mm.
Netro cloud track the moisture level of your soil, rainfall and irrigation watering will increase the moisture level, but high temperature will decrease the moisture level. Once the moisture level is low enough, Netro will water your garden. With different rainfall amount from two weather providers, it may take different time to reach the threshold. That's why one shows 2 days, the other shows 11 days.
But please note that the smart schedules are dynamically adjusted. As we know weather forecast could be inaccurate, especially for 3 days later, Netro updates weather data periodically. If there is significant data change, the smart schedules will be updated accordingly. For example, if Darksky tells us that the rain amount for 08/28 is not 0.8, but 0.1 inch today, Netro will re-calculate smart schedules and may water earlier due to low moisture level. It's not the case that Netro will always water once each 11 days with Darksky but water once every 2 days for AccuWeather.