The Adafruit 4099 sensor measures temperature and humidity using Sensirion’s SHT-30 digital sensor, with an accuracy of ±0.5 °C for temperature and ±2% for relative humidity. Its sintered-mesh metal housing protects against water ingress while allowing air to pass through for measuring ambient humidity. The I2C connection allows you to use code for SHT-3x sensors on microcontrollers.

The sensor can be submerged in water, but prolonged immersion—more than 1 hour at a time—is not recommended; while submerged, it measures temperature only. The cable has four color-coded wires for power, ground, clock, and data, and includes 2.2 kΩ pull-up resistors on SDA and SCL to VCC.

• Type: Thermistor
• Measurements: Temperature and humidity
• Sensor: Sensirion SHT-30
• Temperature accuracy: ±0.5 °C
• Relative humidity accuracy: ±2%
• Interface: I2C
• Protection: Waterproof sintered-mesh metal housing
• Submersion capability: Up to 1 hour at a time
• Power supply: 3–5 V DC
• Cable: 1 m
• Wires: 4 (brown/red: VCC, black: ground, yellow: clock, green/blue: data)
• Pull-up resistors: 2.2 kΩ on SDA and SCL to VCC
• Body dimensions: 14 mm diameter × 50 mm length