How can i reduce drift when calibrating a home weather station barometer?

[Matthew35]

I’ve been trying to calibrate my home weather station’s barometric pressure sensor against a known reference, but my readings keep drifting over a few days. I’m not sure if it’s a sensor stability issue, or if my method for creating a controlled pressure environment using a sealed container and a manual pump is introducing error.

[Justin.L]

I’ve messed with it too. I tried a sealed metal can with a little piston and a hand pump, and I saw drift creep in over days. I kept temperature logs and the can warmed and cooled with the room, and the pressure inside moved with it. It felt like the seal wasn’t perfect, plus gas in a fixed volume is very sensitive to temp. My readings would look stable for hours and then drift by a few tenths of a hectopascal as the day wore on. I stopped treating that setup as a trustworthy reference.

[MiaCT]

I ended up cross-checking with a real reference, not just a pump setup. I used a known calibration pressure from a lab source and compared the readings against a barometric pressure sensor at several temperatures while the two rested at the same temp. Leaks and hose clatter were disasters; the regulator approach and waiting for thermal equilibrium helped more than trying to hold a constant number with a pump.

[Olivia22]

I’m not convinced the problem is only the sensor. The whole chamber idea might be the culprit: tiny leaks, nonuniform pressure, or the gas changing with temperature can mimic drift. It feels like you’re chasing the problem into a corner.

[Andrew70]

I tried a quick tweak: I left the setup in a fridge to keep temps near a fixed point overnight and re-ran the calibration, but the number still wandered a bit. It makes me wonder if the drift is inherent to the weather station’s sensor itself or just measurement noise from the sealed system. If you’ve got a way to compare against a second sensor in the same room, that might reveal which leg is creaking.