Barometric pressure is the pressure created by the weight of the air in Earth’s atmosphere pressing down on a given area, usually measured at the surface of the Earth.

Quick Scoop

What barometric pressure really is

  • It is the same thing as atmospheric pressure: the force exerted by all the air molecules stacked above you, pulled down by gravity.
  • At sea level, an average “normal” barometric pressure is about 1013 millibars (mb) or 29.92 inches of mercury (inHg), sometimes called 1 atmosphere.
  • As you go higher in altitude (up a mountain or in an airplane cabin), there is less air above you, so barometric pressure decreases.

How it’s measured

  • A barometer is the instrument used to measure barometric pressure.
  • Traditional mercury barometers use a column of mercury and report the height of the column in inches or millimeters of mercury.
  • Modern aneroid and digital sensors (including those in smartphones and weather stations) measure the pressure mechanically or electronically and report values in millibars, hectopascals, or inches of mercury.

Why it matters for weather

  • High pressure usually means sinking, denser air and is often linked to clearer, calmer weather.
  • Low pressure is linked to rising air and is often associated with clouds, wind, and stormier conditions.
  • Falling barometric pressure is a classic signal that a storm system or unsettled weather may be approaching; rising pressure suggests improving or more stable conditions.

Everyday and modern uses

  • Meteorologists track pressure patterns (highs and lows) to forecast fronts, storms, and large-scale weather systems.
  • Pilots rely on pressure readings to set altimeters and safely determine altitude in aviation.
  • Barometric pressure is also monitored in environmental science, marine navigation, and sometimes in studies of human comfort and health (for example, how some people feel headaches or joint pain when pressure changes).

A simple way to picture it: imagine the atmosphere as an ocean of air. Barometric pressure tells you how “deep” you are in that ocean—higher pressure is like being deeper under the air, lower pressure is like being higher up where there’s less air above you.

TL;DR: Barometric pressure is the measure of how hard the atmosphere is pressing on you, recorded by a barometer, and it’s one of the key numbers used to understand and predict weather.

Information gathered from public forums or data available on the internet and portrayed here.