Temperature and humidity measurements are a nice addition ... He decided to take an in-depth look at the DHT11 sensor; which you can get your hands on for under $3 if you know where to look.

To build your very own IoT rain checking system, you will need a Raspberry Pi 3 Model B, a DHT11 Temperature & Humidity Sensor (4 pins), and a raindrop sensing board, which can be purchased for ...

Using a bespoke weather station sensor can give you accurate temperature, atmospheric pressure, and humidity ... to build a Raspberry Pi-based weather station include: Two 4.7k Ohm resistors.