What is the accepted difference between an aneroid barometer and an official weather station?

Good Day,

Can you tell me please what is the accepted difference between an aneroid barometer for homes and an official weather station in let’s say mbar please ? I mean how much is normal for a barometer to be plus or minus for atmospheric pressure reading compared to an official weather station taking in account that the home barometer is not defect. What did you observe or read about that please ?

What are the causes that an aneroid barometer has less precise values than an official weather station besides the factory precision of the two instruments which with they left it. What piece from aneroid barometer is responsible for accuracy ?

Thank you !

A good quality aneroid barometer should be able to get within +/- 1 mbar/hPa of the true atmospheric pressure in a location. Knowing whether a barometer is good quality and well maintained is more difficult to decide!

If you’re trying to compare a barometer in a location with the pressure given by an ‘official’ source, e.g. an airport METAR, then you need to bear in mind a couple of things…

  1. How far you are from the other location. The pressure can vary fairly significantly at times over 20-30 km so if you’re a fair distance away that could have an impact. There’s no easy way to know what the difference due to location is likely to be though. In most cases if you’re within 10km of the source then you should be fairly close to that value.

  2. Is the ‘official’ source giving the Pressure at Mean Sea Level (PRMSL or in aviation terms QNH), i.e. local pressure adjusted to sea level based on the height of the recording station? If it is then you need to be aware that your house based barometer will be measuring local pressure (known as QFE) at whatever altitude (height above sea level) you’re at. Pressure reduces by approximately 1mbar/hPa for each 10m of height. So if the official station is giving a PRMSL/QNH of 1000 mbar/hPa then if your barometer is at 100m above sea level your local reading would be about 990 mbar/hPa. Most personal weather stations will allow this to be adjusted, but I suspect that most aneroid barometers won’t have such an adjustment.