Live barometric pressure for your location or any city worldwide — atmospheric pressure in hPa and inHg, rising/falling trend, 24-hour chart, and instant weather interpretation.
This online barometer delivers real-time barometric pressure for your exact location or any city worldwide using live weather data from Open-Meteo. It displays current atmospheric pressure in both hectopascals (hPa) and inches of mercury (inHg), a rising or falling pressure trend, a 24-hour pressure history chart, and an instant weather interpretation — all in a realistic analog dial presentation.
Barometric pressure, also called atmospheric pressure, is the force exerted by the weight of the air column above a point on Earth's surface. It is the foundational measurement in meteorology because pressure differences drive wind, influence cloud formation, and are the earliest indicator of approaching weather changes. Standard atmospheric pressure at sea level is 1013.25 hPa (29.92 inHg).
The analog dial shows pressure from 940 hPa on the left through to 1060 hPa on the right. Coloured zones indicate weather likelihood: the stormy zone (deep red, 940–980 hPa) signals low pressure and unsettled conditions; the change zone (amber, 980–1020 hPa) indicates variable weather; the fair zone (green, 1020–1050 hPa) signals high pressure and clear skies. The needle points to the current live reading, and the trend arrow shows whether pressure is rising, falling, or holding steady.
A rising barometer generally indicates improving weather — high pressure pushing away clouds and precipitation. A rapidly rising pressure (more than 3 hPa in 3 hours) can signal the passage of a cold front. A falling barometer signals deteriorating weather ahead, with rain and wind likely as a low pressure system approaches. A rapidly falling pressure (more than 3 hPa in 3 hours) is a strong warning of severe weather incoming. Steady pressure usually means current conditions will persist.
Hectopascals (hPa) are the internationally standard unit used in meteorology worldwide. Inches of mercury (inHg) are the traditional unit used in aviation and in the United States. Both measure the same thing: 1013.25 hPa equals 29.92 inHg. To convert: multiply hPa by 0.02953 to get inHg, or divide inHg by 0.02953 to get hPa. This barometer displays both simultaneously.
Pressure below 980 hPa is associated with storms and severe weather. Pressure between 980 and 1000 hPa typically means rain or wind is likely. The 1000–1020 hPa range is the most variable zone — weather can go either way depending on pressure direction. Pressure between 1020 and 1040 hPa suggests fair, settled conditions. Above 1040 hPa indicates very high pressure, which often means exceptionally clear and dry weather, though prolonged high pressure can bring drought conditions in summer.
This page detects your location automatically using your browser's geolocation, or you can search for any city by name. You can also enter precise latitude and longitude coordinates to check barometric pressure for any point on Earth, including offshore locations. Use the quick city buttons for instant readings in major world cities.
Mariners and pilots rely heavily on barometric pressure readings. Rapidly falling pressure at sea signals approaching storms and dangerous conditions. Pilots use pressure altimeter settings (QNH) derived from sea-level pressure to calibrate aircraft altimeters. For maritime conditions including wave height, swell, and sea state, visit the maritime weather page.
The barometer works alongside other instruments for complete weather monitoring. Use the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, and the wind vane for wind direction. Together they provide a complete picture of current atmospheric conditions.
A barometer is a scientific instrument that measures atmospheric pressure — the weight of the air above a given point. The word comes from the Greek baros (weight) and metron (measure). The barometer definition in meteorology refers specifically to a device that quantifies how heavy the atmosphere is pressing down at that moment, expressed in hPa, mb, or inHg. The meaning of barometer in everyday language has also come to represent any indicator of change — a "barometer of public opinion," for example — but in weather science it refers precisely to this pressure measurement instrument.
What is a barometer? It is an instrument that measures the pressure exerted by the atmosphere at a specific location and time. What is barometer used to measure, specifically? It measures the force per unit area applied by the air column above, expressed in hectopascals (hPa) or inches of mercury (inHg). What does a barometer measure in practical terms? It measures whether air pressure is high, normal, or low — giving forecasters and individuals an immediate indicator of what weather is coming. A weather barometer is one of the three core instruments in any weather station, alongside the thermometer and hygrometer.
The use of barometer instruments spans meteorology, aviation, marine navigation, mountaineering, and scientific research. In weather forecasting, a barometer is used to track pressure trends that precede storms or fair weather. In aviation, the barometer is used to derive altimeter settings — pilots set their altimeters to the local pressure to ensure accurate altitude readings. At sea, the barometer is used to give early warning of approaching gales. In mountaineering, barometer pressure drops with altitude, so the instrument is used to track elevation gain. The barometer is used for all these purposes because pressure is one of the atmosphere's most reliable and measurable properties.
The two main types of barometer are the mercury barometer and the aneroid barometer. The mercury barometer, invented by Evangelista Torricelli in 1644, uses a vertical glass tube sealed at the top and submerged in a mercury reservoir. Atmospheric pressure pushes down on the mercury in the reservoir, forcing it up the tube — the height of the mercury column directly measures pressure. At standard pressure, mercury stands at 760 mm (29.92 inches), giving the inHg unit its meaning. The mercury barometer is highly accurate but fragile and contains toxic mercury, limiting its use.
The aneroid barometer, invented in 1844 by Lucien Vidie, replaces mercury with a sealed, flexible metal capsule (the aneroid cell) that expands and contracts as pressure changes. A mechanical linkage amplifies and displays this movement on a dial. Aneroid barometers are compact, portable, and safe, making them the dominant type for home, marine, and field use. The word aneroid means "without liquid." Most household barometers and all barometer watches use the aneroid principle. The aneroid barometer uses for modern applications also include aircraft altimeters and weather stations.
A digital barometer uses an electronic pressure sensor — typically a MEMS (micro-electromechanical system) sensor — to measure atmospheric pressure and display it on a screen. Digital barometers are more precise than mechanical aneroid instruments and can record pressure over time for trend analysis. A barometer app on a smartphone uses the phone's built-in pressure sensor (available on most iPhones since iPhone 6 and on many Android devices) to display live pressure readings. The iPhone barometer sensor is primarily used by Apple for altitude tracking in fitness apps. The Android barometer serves similar purposes. However, smartphone barometer sensors are less accurate than professional instruments because they measure pressure inside the phone casing rather than the open air. This online barometer uses high-quality weather station data for reliable readings.
A barometer watch is a smartwatch or outdoor sports watch that incorporates a barometric pressure sensor. Popular barometer watches include models from Garmin, Suunto, Casio Pro Trek, and Apple Watch. They display current pressure, trend arrows, and altitude estimates — all derived from the same aneroid or digital sensor principle. Barometer watches are particularly popular with hikers, climbers, and sailors who need portable, wrist-worn pressure monitoring. The barometer watch market has grown significantly as outdoor sports watches have become mainstream.
Barometric pressure today for your location is displayed live at the top of this page, updated each time you load or refresh. The reading shows current hPa and inHg values alongside a 3-hour trend to indicate whether barometric pressure today is rising, falling, or steady. The 24-hour chart below the instrument shows how atmospheric pressure has moved throughout the day. If you want barometric pressure today for a specific city — London, New York, Dubai, Tokyo, or any other — use the search bar or city buttons above.
Air pressure definition: the force per unit area exerted by the atmosphere on any surface it contacts. Air pressure is caused by the weight of the air above — at sea level, a column of air stretching to the top of the atmosphere presses down with about 101,325 Pascals (1013.25 hPa) of force per square metre. What is air pressure in simple terms? It is how hard the air is pushing against everything around you. Higher air pressure means denser, heavier air above; lower air pressure means thinner, lighter air. Air pressure decreases with altitude, which is why mountain summits have lower pressure than sea level, and why aircraft cabins must be pressurised.
Because air pressure decreases predictably with altitude, barometric pressure can be used to estimate elevation. An altimeter is essentially a barometer calibrated in units of altitude rather than pressure. Every 8.5 metres of ascent at sea level corresponds to approximately 1 hPa of pressure drop. Aircraft altimeters are set to local sea-level pressure (QNH) so that altitude readings remain accurate relative to terrain. Hikers use barometric altimeters to track their elevation during ascents. This relationship between barometer pressure and altitude is one of the most practical applications of atmospheric measurement.
A weather barometer is specifically used to make short-term weather forecasts based on pressure trends. Traditional weather barometer dials are marked with words like "Stormy," "Rain," "Change," "Fair," and "Very Dry" corresponding to pressure zones. While these zone labels are simplified, they reflect genuine meteorological relationships: low pressure systems bring unsettled, wet, and windy weather; high pressure systems bring calm, clear conditions. A weather barometer is most useful not for its absolute reading but for the direction and speed of change. A barometer dropping 3 hPa or more in three hours is a standard meteorological warning of approaching severe weather.
Barometer pressure is measured on a continuous scale. The lowest pressures ever recorded on Earth were in powerful tropical cyclones — Typhoon Tip in 1979 reached 870 hPa. The highest pressures occur in Siberian winter high-pressure systems, sometimes exceeding 1084 hPa. For everyday weather at temperate latitudes, barometer pressure ranges between about 970 hPa (deep Atlantic low) and 1040 hPa (blocking high). The standard sea-level pressure of 1013.25 hPa is the midpoint that defines "normal." This online barometer displays the full practical range from 940 to 1060 hPa on its dial.
How to read a barometer for weather purposes requires understanding both the current reading and the direction of change. Check the pressure at the same time each day and note whether it has risen or fallen. A steady fall over 6–12 hours of 4–8 hPa or more indicates an approaching low-pressure system and likely rain or wind. A steady rise of similar magnitude after a period of low pressure means the low is departing and clearer weather is coming. A rapid fall — more than 6 hPa in 3 hours — is a gale warning in maritime contexts. Pressure that has been steady for several days in the high-pressure range (above 1020 hPa) generally means settled weather will continue.
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