The SHT31 is a Sensirion temperature and humidity sensor, and it is the one to buy when the reading matters. It is markedly more accurate than a DHT22, about a third of a degree and two percent humidity, reads quickly over the tidy I²C bus, and costs only a few dollars more. For climate control, VPD, and anything you act on, it is the sweet spot between cheap and trustworthy.
What it is.
The SHT31 is a small, well-made digital sensor that reports calibrated temperature and humidity over I²C. Its accuracy is the headline: roughly ±0.3 °C and ±2 % RH, good enough to trust for a decision rather than just a trend. It also carries a small onboard heater you can pulse to drive off condensation in a damp space, which keeps the humidity element honest in a greenhouse. Sensirion’s reputation for sensor quality is a big part of why it is the common recommendation.
Key facts.
How to wire it.
Four wires over I²C: VCC, GND, and the two I²C lines SDA and SCL to your microcontroller. Being I²C, it shares those two lines with other I²C sensors, and its address is 0x44 or 0x45. ESPHome has it built in, and there are one-line Arduino libraries. There is little to trip over here, which is part of the appeal: it just works, and the numbers it returns are ones you can rely on.
Where it fits, and where it doesn’t.
Where it fits
- Readings you act on: climate control, VPD.
- Greenhouses and grow rooms that need honest humidity.
- Damp spaces, using the heater to clear condensation.
- I²C setups sharing a bus with other sensors.
Where it doesn’t
Related options.
The SHT31 is the accuracy pick for temperature and humidity. Add a BME280 if you also want barometric pressure, or save a little with a DHT22 where rough is fine. See them side by side on the family overview.
Datasheet & where to buy.
Sensirion SHT31 Where to buy Compare temp & humidity sensors
Frequently asked questions.
Is the SHT31 better than the DHT22?
For accuracy, clearly yes. The SHT31 is about plus or minus 0.3 degrees C and 2 percent humidity, against the DHT22 at 0.5 degrees and 2 to 5 percent, and it reads faster over I2C. It costs a few dollars more. Choose the SHT31 when the reading drives a decision; the DHT22 is fine for rough hobby use.
What is the SHT31 heater for?
It is a small onboard heater you can pulse to drive condensation off the sensor in a damp environment. In a humid greenhouse, briefly heating the element clears moisture so the humidity reading stays accurate. You leave it off in normal use.
What is the SHT31 I2C address?
It is 0x44 by default, or 0x45 if the address pin is set high, which lets you run two on one bus. Set the right address in your library if the default does not respond.
Does the SHT31 measure pressure?
No, only temperature and humidity. If you also want barometric pressure, use a BME280, which adds pressure at slightly lower temperature and humidity accuracy.
Is the SHT31 good for VPD?
Yes, it is a strong choice. VPD is calculated from temperature and humidity, so its accuracy on both gives a VPD figure you can actually act on, which is why it suits climate control in a tunnel or grow room.