Build a Smart Temperature & Humidity Monitor with Arduino – Step-by-Step Guide

Introduction

Monitoring temperature and humidity is one of the most popular beginner Arduino projects — and for good reason. Whether you're building a smart home system, a plant monitor, or a weather station, this project teaches you core skills like sensor interfacing, LCD display output, and serial communication.

In this guide, we'll build a complete Temperature & Humidity Monitor that displays live readings on a 16×2 LCD screen, with all components available at Anil Electronic Store.

What You'll Build

• A live temperature & humidity display on a 16×2 LCD
• Optional serial monitor output for logging
• Runs on 5V USB power — no external supply needed
• Total build time: ~30 minutes

Components Required (BOM)

All components below are available in stock at anilestore.com. See the kit panel on this page to add everything in one click.

Circuit Connections

DHT22 Sensor → Arduino Uno:

• VCC → 5V
• GND → GND
• DATA → Digital Pin 2

LCD 16×2 (via I2C Module) → Arduino Uno:

• VCC → 5V
• GND → GND
• SDA → A4
• SCL → A5

Arduino Code

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>

#define DHTPIN 2
#define DHTTYPE DHT22

DHT dht(DHTPIN, DHTTYPE);
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  dht.begin();
  lcd.init();
  lcd.backlight();
  lcd.print("Temp & Humidity");
  delay(2000);
  lcd.clear();
}

void loop() {
  float h = dht.readHumidity();
  float t = dht.readTemperature();

  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.print(t);
  lcd.print(" C");

  lcd.setCursor(0, 1);
  lcd.print("Humidity: ");
  lcd.print(h);
  lcd.print("%");

  delay(2000);
}

Required Libraries

Install these from the Arduino IDE Library Manager:

• DHT sensor library by Adafruit
• LiquidCrystal_I2C by Frank de Brabander
• Adafruit Unified Sensor

Go to Sketch → Include Library → Manage Libraries and search for each one.

Step-by-Step Assembly

1. Insert the Arduino Uno into your breadboard or place it on your workbench.
2. Connect the DHT22 sensor — pin 1 to 5V, pin 2 to D2 (with 10kΩ pull-up resistor between pin 2 and 5V), pin 4 to GND.
3. Connect the I2C LCD module — SDA to A4, SCL to A5, VCC to 5V, GND to GND.
4. Use jumper wires on the breadboard to keep connections clean.
5. Upload the code via USB and open the Arduino IDE Serial Monitor at 9600 baud to verify readings.

Troubleshooting Tips

• LCD shows nothing? Adjust the contrast pot on the back of the I2C module.
• DHT22 returns NaN? Check the pull-up resistor on the data line and ensure correct pin number in code.
• Wrong I2C address? Run an I2C scanner sketch to find your LCD's address (common values: 0x27 or 0x3F).

Upgrades & Next Steps

• Add a NodeMCU ESP8266 to send data to a cloud dashboard (Blynk / ThingSpeak)
• Add a buzzer to alert when temperature crosses a threshold
• Use a DS3231 RTC module to log readings with timestamps
• Replace the LCD with an OLED display for a sleek look

Conclusion

This project is a fantastic starting point for anyone exploring Arduino and IoT. With just a few components from Anil Electronic Store, you can have a working monitor in under an hour. All parts in the BOM are in stock and ship same day for orders placed before 2 PM.

Questions? Chat with our engineer on WhatsApp — we're happy to help with circuit doubts and code issues!