Can I add more sensors?

Yes. Add a wind sensor or rain gauge to the same setup.

How often does it update?

Every 15 seconds by default. Change the number in the code.

No. It works completely offline. You can add WiFi later.

All guides

beginner10 September 2026

Build a Weather Station

Desktop weather station with ESP32, BME280 sensor and OLED display.

What you’ll build

A small box that sits on your desk and shows you the temperature, humidity and air pressure in real time. You’ll learn how sensors work, how to wire them up, and how to write code that reads data.

Before you start: Can you guess which sensor measures humidity? The BME280 measures all three — temperature, humidity and pressure. It’s the same chip inside many smart home devices.

What you need

Buy these parts individually — none of this comes in a kit:

Part	What it does	Photo
ESP32 dev board	The brain — runs your code
BME280 sensor	Reads temp, humidity, pressure
0.96” OLED display	Shows the readings
Breadboard	Lets you wire without soldering
Jumper wires	Connect everything
USB-C cable	Power and programming

💡 Not sure what to buy? Search for “ESP32 dev kit” on any electronics shop — you want the one with 38 pins. For the BME280, search “BME280 module” — it has 4 pins already soldered on.

Step 1: Find the pins

Before wiring, let’s understand what you’re looking at.

On the ESP32 board:

Look for a pin labelled 3.3V — this is power
Look for GND — this is ground (the return path)
Find GPIO 21 and GPIO 22 — these carry data
Find A0 — this reads analog signals

🤔 Can you find them? Take 30 seconds to locate all five pins on your board. Check with a friend — did you find the same ones?

On the BME280 sensor: You’ll see 4 pins: VCC, GND, SDA, SCL.

On the OLED display: You’ll see 4 pins: VCC, GND, SDA, SCL.

💡 Why two SDA and two SCL? Both the sensor and the display use the same “I2C” communication protocol. They share the two data wires — that’s fewer wires you need to connect!

Step 2: Wire it up

Here’s the wiring. Follow it exactly:

  ESP32           Breadboard           BME280           OLED
  ──────           ──────────           ──────           ────
  3.3V  ──────→   + rail     ──────→  VCC            VCC
  GND   ──────→   - rail     ──────→  GND            GND
  GPIO21 ──────→               ──────→  SDA            SDA
  GPIO22 ──────→               ──────→  SCL            SCL

🤔 Why does GPIO 21 and 22 go to both the sensor AND the display? They’re on the same I2C bus — like two people listening to the same radio. Each device has a different address, so the ESP32 knows which is which.

Colour code your wires

Use wire colours consistently — it makes troubleshooting much easier:

Colour	Purpose	Where it goes
Red	Power (3.3V)	ESP32 → 3.3V rail → VCC on both devices
Black	Ground (GND)	ESP32 → GND rail → GND on both devices
Yellow	Data (SDA)	ESP32 GPIO 21 → SDA on both devices
Green	Data (SCL)	ESP32 GPIO 22 → SCL on both devices

✅ Test it now: Before writing any code, plug in the USB cable. Does the ESP32 power up? If you have an LED on the board, it should light up. If nothing happens, double-check your power connections.

Step 3: Install the libraries

Libraries are pre-written code that handles the hard parts for you.

Open Arduino IDE
Go to Sketch → Include Library → Manage Libraries
Search for and install each one:

Library name	What it does
Adafruit SSD1306	Controls the OLED display
Adafruit GFX Library	Graphics helpers for the display
Adafruit BME280	Reads the BME280 sensor

🤔 What is a library? Think of it like a cookbook — instead of writing every recipe from scratch, you flip to the page that already has it done.

Step 4: Upload the code

Copy this into Arduino IDE:

#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_BME280.h>

Adafruit_SSD1306 display(128, 64, &Wire, -1);
Adafruit_BME280 bme;

void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  if (!bme.begin(0x76)) {
    display.println("Sensor not found!");
    display.display();
    while (1) delay(100);
  }
}

void loop() {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.print("Temp: ");
  display.print(bme.readTemperature(), 1);
  display.println(" C");
  display.setCursor(0, 12);
  display.print("Hum:  ");
  display.print(bme.readHumidity(), 1);
  display.println(" %");
  display.setCursor(0, 24);
  display.print("Pres: ");
  display.print(bme.readPressure() / 100.0, 1);
  display.println(" hPa");
  display.display();
  delay(15000);
}

What each part does:

#include lines — loads the libraries (like opening the cookbook)
Adafruit_SSD1306 display(...) — creates a display object (like naming your screen “display”)
bme.begin(0x76) — starts the sensor at address 76 (check yours — some are 0x77)
display.print(...) — shows text on the screen
delay(15000) — waits 15 seconds before updating (15000 milliseconds)

🤔 What do you think 0x3C means? It’s the OLED’s address on the I2C bus — like a house number. If your display doesn’t work, try 0x3D — some displays use that address instead.