Air pressure decreases with altitude, so if you live in an elevated location you will have a lower pressure than places at sea level. The correct local pressure is called Station Level Pressure. It can?t, however, be compared with Mean Sea Level Pressure. The pressures you see on Weatherzone have all been corrected to MSLP. It is therefore most useful if you set your barometer to MSLP. You will then be able to compare your pressure with the weather charts and observations on the website.
To do this, find your current pressure on Your Local Weather Page. If there is no observation for the town in which you live, use the observation for the nearest available station. Set your barometer to the pressure given. You will be able to move the pointer with a screw in the back of the barometer. It is not the pointer at the front that you want to move.
Check your barometer 24 hours later against the observations to ensure that it has remained calibrated. It should only need to be adjusted by a small amount, if at all. Regularly check your barometer against the official readings provided on the website. You should generally do this during periods of stable weather when the pressure is not changing rapidly.
11:16 EDT Thick fog engulfed the Sydney Basin on Saturday morning dropping visibility as low as 100m in some suburbs.