Here is another smart sensor that can monitor temperature and humidity and make the data available on your phone. The Tempy.io 2 comes with iOS and Android app control. It makes temperature, humidity, dew point, and air-pressure readings available on your phone and has a gateway with a range of 4000ft.
The sensors last up to 10 years on AA batteries. An unlimited # of sensors can be managed using a single Tempy account.