Troubleshooting DHT22 Sensor Fluctuations in Arduino Climate Monitoring Project

[katie1]

Hi everyone,

I’ve been experimenting with a DHT22 temperature and humidity sensor for a small indoor climate monitoring setup, but I’m noticing some inconsistencies in readings and would love some input from others who’ve worked with these sensors before.

Setup Details:

• Arduino Uno
• DHT22 sensor (3-pin version) connected to digital pin 7
• 10kΩ pull-up resistor between VCC and data line
• 5V regulated power supply
• Data logged to an SD card module and displayed on a 0.96" OLED
• Testing indoors under stable room temperature and humidity

What I’m Seeing:

• Temperature readings vary by ±1.5°C between consecutive measurements even in a stable environment.
• Humidity values fluctuate more than expected (sometimes ±4–5%).
• Occasionally, the DHT22 fails to return valid data (“NaN” or checksum errors).
• Readings seem slightly delayed or laggy when compared to a commercial hygrometer.

What I’ve Tried So Far:

• Added decoupling capacitors (100nF + 10µF) near the sensor’s power pins.
• Verified wiring and data pin pull-up resistance.
• Tried both the Adafruit DHT library and the DHTesp library — similar behavior.
• Placed the sensor in a small ventilated enclosure to reduce airflow effects.
• Tested with two different DHT22 units to rule out sensor damage.

My Questions:

1. Is this level of fluctuation typical for DHT22 sensors, or should I expect tighter accuracy?
2. Would adding time-based averaging or exponential smoothing help stabilize readings?
3. How sensitive is the DHT22 to power supply noise — would a separate regulator help?
4. Are there better alternatives (like SHT31, BME280, or AHT20) for more reliable temperature/humidity data?
5. Any tips for improving long-term stability when the sensor runs continuously indoors?

Thanks in advance!

I’d love to make this setup stable before expanding it into a multi-room environmental monitoring system.