In my experience, just spend one afternoon in the calibration process.
Heat the oven up to 55 degrees and switch it off, put your electronics inside. Start to log your sensors,
once you reach the room temperature, put your electronics in a fridge/freezer (down to -5?).
The behavior of the readings with the temperature should be almost linear. Compute the slope and the off-set (bias).
Do the whole process again (as many times as you can, but with only one should be enough).
Make a simple routine for interpolation or extrapolation.
Also you can fit your curve to a quadratic one, that depends on you, but the Kalman filter should take care about this deviations.