A weather station is a fun project that teaches you a ton about electronics with the added benefit being an actually useful little device. Instructables user Ingenerare has a guide for making your own little tiny weather station on the cheap.
The project requires a bunch of cheap parts and sensors totaling less than $US20 ($27), and the whole thing ends up fitting in your hand. The station creates a web site that monitors temperature, dew point, humidity, pressure, light index, and rain. It's a pretty easy set up, and you'll just need some basic electronics skills to get it going. Head over to Instructables for the full guide.
Easy IoT Weather Station [Instructables]