BME280 callibration- modifying the temperature changes the pressure reading?

Hi everyone,

Bit of Noob here so be gentle. I’ve successfully added a BME280 temperature, humidity and pressure sensor to HA. The temperature readings are too high so I added (as per the guide in HA here the following line to the configuration.yaml file:

     - platform: bme280
       delta_temperature: -2.5

This brings the temperature reading into line with other thermometers, but also seems to have done the same with my pressure readings:

I can’t see how this could happen. There’s a double step change in the above graph as I made another deta_temperature change to see what would happen, and as you can see it stepped down with a D-temp of -3.5, and jumped up when I changed it to -2.5. Very strange!

Any ideas on how to limit the change to temperature readings or is this a limitation of the BME board?

Thanks in advance,


The ideal gas law. PV=nRT.

Pressure (P) is temperature (T) dependant. There’s a calibration factor dependant on temperature of the device.

Wow, that is a brilliant answer, thanks! The board is much smarter than I imagined. I’d assumed it would just measure them mechanically so there’s a lot of learning here. Thanks again!

Does the pressure reading line up with what your weather service is saying?

Actually if doesn’t seem too. Right now the Met Office UK and both say it should be 1021, but I’m reading 990. So that’s quite a bit out.

Pressure is also dependent on altitude, not sure if the integration takes that into account. In comparison ESPHome explains in a bit more detail how you could adjust the readings: BME280 Environment — ESPHome

Thanks, that’s very useful. Much appreciated!