Fig. Block diagram of a weather station
1. Sensors
I used 3 sensor modules which can be acquired via ebay or aliexpress. It seems they are cheap Chinese clones of well known sparkfun/adafruit modules. Also I made a simple sensor to monitor battery voltage. (Someone should keep a Li-ion battery above 3V level.) You can easily find arduino libraries for these modules. So modules can be used at once. But keep in mind a "chinese clone" sensor can use a different I2C address. So you may need to run an arduino script that called I2C scanner to identify these addresses and then change a device I2C address constant in a library header file to guarantee correct work the library with the module.
I used the following devices
