Design
Weather Station Monitoring System
Design a weather station that reads sensor data and pushes updates to multiple displays in real time.
This is a Low-Level Design (LLD) problem. New to LLD vs HLD? Start here.
01 - Why interviewers ask this
It's the textbook Observer pattern demonstration — interviewers use it to confirm you understand Subject/Observer decoupling before it shows up disguised inside a bigger system design.
02 - Where this system exists in the real world
You interact with this design every day.
IoT sensor dashboards and monitoring tools
Stock ticker / live data display systems
Weather app widgets with multiple display formats
03 - What you'll master
Solve this once. Know it forever.
Implement the Observer pattern from scratch
Decouple a data source from its displays
Maintain incremental running statistics
04 - What you'll design
5 functional · 2 non-functional requirements.
Collect temperature, humidity, and pressure readings
4 more requirements inside
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05 - Companies that ask this
You may face this exact question in your next interview.
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