A barometer is a tool that measures air pressure in our atmosphere, which in turn helps predict weather. A properly set up barometer gives an accurate reading and allows you to determine when clear, cloudy, or rainy weather will occur within a 12- to 24-hour window. Setting up a barometer, in this case one that is analogue, requires only a flathead screwdriver and a check of the local weather conditions.
Wait until the weather in your area is stable before setting the barometer. Stable weather generally means that there is no wind.
Check online for your local weather forecast (see National Weather Service link in Resources below), or refer to your local television news channel weather report to find out what the barometric reading is for your area. You can also call a nearby airport to find out what conditions they are reporting. To be sure, check with all of these resources for the best real time weather forecast. Realise that reports will vary, so choose a reading from a source that is closes to your location, approximately within a 20-mile radius.
Use a flathead screwdriver to change the hand if needed. Turn the hand in a clockwise direction until the hand matches up to the current reading that you determined from the Internet, news, airport or other source. Generally there is a spot on the back of the barometer, with a small hole, where you can insert the screwdriver and turn the barometer hand.
Tap on the glass very gently to ensure that the hand is set at the correct reading. This is basically calibrating the barometer.
Check the barometer every 2 weeks to make sure that it is still set correctly, or calibrated. Check your reading and compare it to one of your weather sources (Internet, news channel or airport).
Hang the barometer in a conveniently located place. Air pressure is the same both inside and outside, so it does not matter where you hang the barometer.
You do not need to know your altitude to set a barometer.