Build a WiFi Weather Station with Arduino & BME280

Monitor your local weather with a sensor that costs less than a cup of coffee. The BME280 measures temperature, humidity, and barometric pressure with impressive accuracy.

Bill of Materials

Wiring

Both the BME280 and OLED use I2C, so they share the same two data lines:

ESP32 GPIO21 (SDA) → BME280 SDA → OLED SDA
ESP32 GPIO22 (SCL) → BME280 SCL → OLED SCL
ESP32 3.3V → BME280 VCC → OLED VCC
ESP32 GND → BME280 GND → OLED GND

The Code

Install these libraries via Arduino Library Manager:

• Adafruit BME280 (and Adafruit Unified Sensor)
• Adafruit SSD1306 (and Adafruit GFX)
• WiFi (built into ESP32 core)

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

Adafruit_BME280 bme;
Adafruit_SSD1306 display(128, 64, &Wire);
WebServer server(80);

const char* ssid = "YOUR_WIFI";
const char* password = "YOUR_PASSWORD";

void setup() {
  Serial.begin(115200);
  Wire.begin();

  bme.begin(0x76);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);

  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) delay(500);

  server.on("/", []() {
    float temp = bme.readTemperature();
    float hum = bme.readHumidity();
    float pres = bme.readPressure() / 100.0;

    String html = "<h1>Weather Station</h1>";
    html += "<p>Temperature: " + String(temp, 1) + " C</p>";
    html += "<p>Humidity: " + String(hum, 1) + " %</p>";
    html += "<p>Pressure: " + String(pres, 1) + " hPa</p>";
    server.send(200, "text/html", html);
  });

  server.begin();
  Serial.println("Server at: http://" + WiFi.localIP().toString());
}

void loop() {
  server.handleClient();

  // Update OLED every 2 seconds
  static unsigned long lastUpdate = 0;
  if (millis() - lastUpdate > 2000) {
    lastUpdate = millis();
    display.clearDisplay();
    display.setTextColor(WHITE);
    display.setTextSize(1);
    display.setCursor(0, 0);
    display.printf("Temp: %.1f C\n", bme.readTemperature());
    display.printf("Hum:  %.1f %%\n", bme.readHumidity());
    display.printf("Pres: %.0f hPa\n", bme.readPressure() / 100.0);
    display.printf("\nIP: %s", WiFi.localIP().toString().c_str());
    display.display();
  }
}

Taking It Further

• Data logging: Push readings to InfluxDB + Grafana for beautiful time-series charts
• Alerts: Send a Telegram notification when pressure drops rapidly (storm incoming!)
• Solar power: Add a TP4056 charge controller and 18650 battery for off-grid operation
• Multi-sensor: Daisy-chain multiple BME280s at different I2C addresses for indoor/outdoor comparison