Build a Cloud-Connected Weather Station with Arduino UNO R4 WiFi
Learn how to build a real IoT weather station using the Arduino UNO R4 WiFi and BME280 sensor, sending live temperature, humidity, and pressure data to Arduino IoT Cloud — with full code, wiring diagrams, and dashboard. What We're Building In this project, you'll build a cloud-connected weather station that measures: Temperature (°C / °F) Humidity (%) Atmospheric Pressure (hPa) All three readings will be streamed live to the Arduino IoT Cloud , where you can monitor them from anywhere in the world via a browser or the free Arduino IoT Remote app on your phone. Components Required Component Qty Notes Arduino UNO R4 WiFi 1 Built-in ESP32-S3 WiFi module BME280 Sensor Module 1 Measures temp + humidity + pressure via I²C Breadboard 1 Full or half size Jumper Wires (M-M) 4 For I²C connections USB-A to USB-C Cable 1 For power & programming Why BME280 over DHT22? The BME280 gives you three measurements (including barometric pressure) over a single I²C bus using just 2 wires, making it more capable and cleaner to wire. The DHT22 only gives temperature and humidity. Wiring the BME280 to Arduino UNO R4 WiFi The BME280 uses the I²C protocol , so it only needs 4 wires: BME280 Pin → Arduino UNO R4 WiFi Pin ────────────────────────────────────── VCC → 3.3V GND → GND SDA → A4 (I²C Data) SCL → A5 (I²C Clock) Important: The BME280 runs on 3.3V , not 5V. Connecting it to the 5V pin can damage the sensor permanently. Here's the schematic overview: ┌────────────────────────────┐ │ Arduino UNO R4 WiFi │ │ │ │ 3.3V ──────────────► VCC │ │ GND ──────────────► GND │ ← BME280 │ A4 ──────────────► SDA │ │ A5 ──────────────► SCL │ └────────────────────────────┘ ☁️ Step 1 — Set Up Arduino IoT Cloud Before writing any code, you need to configure the Arduino IoT Cloud . It's free for up to 2 devices. 1.1 Create a Free Account Go to cloud.arduino.cc and sign up or log in. 1.2 Create a New "Thing" Click Things in the left sidebar Click + Create Thing Name it WeatherStation 1.3 Add Your Device Click