Adafruit HDC3021 Precision Temperature & Humidity Sensor - STEMMA QT / Qwiic

The HDC3021 sensor module is designed to operate from a 3.3V DC supply, which is provided via the STEMMA QT / Qwiic connector. It is compatible with both 3.3V and 5V logic microcontrollers, as the I2C lines include level shifting. Always ensure your host board provides the correct 3.3V power on the connector.

Connection is solderless using a STEMMA QT or Qwiic cable between the sensor and a compatible Arduino board (e.g., Adafruit QT Py or boards with a Qwiic/STEMMA QT port). For software, install the Adafruit HDC3021 library via the Arduino Library Manager. The library provides example code to initialize the sensor over I2C and read temperature and humidity values with simple function calls.

Accuracy (±0.5% RH typical) refers to the sensor's immediate measurement error compared to a known reference under specific conditions. Long-term drift (0.19%RH/year) indicates how much the sensor's calibration may shift over extended operational time and environmental exposure. The HDC3021 offers excellent stability, meaning its readings remain trustworthy over long periods without frequent recalibration.

The HDC3021 sensor IC itself has a wide operating temperature range (-40°C to +125°C), making it suitable for many outdoor and industrial environments. However, the module PCB is not conformally coated or rated for specific IP protection against water and dust. For permanent outdoor installation, consider housing the module in a protective, ventilated enclosure that shields it from direct moisture and condensation while allowing air exchange for accurate sensing.