Barometric pressure changes constantly based on your location, elevation, and current weather systems, so no single number applies everywhere at once. To find the reading for your area right now, the quickest option is to search “barometric pressure [your city]” or check a weather app like Weather Underground, which reports real-time pressure from local stations. Many smartphones also have a built-in barometer sensor in their weather or compass apps. Once you have your number, the guide below will help you understand exactly what it means.
What Counts as Normal Barometric Pressure
Standard atmospheric pressure at sea level is 29.92 inches of mercury (inHg), or 1013.25 millibars (also written as hectopascals, or hPa). These two units show up most often on weather sites and home barometers. If your reading is close to 29.92 inHg, conditions are roughly average for a sea-level location.
Most pressure readings you see on weather apps are not raw measurements. They’ve been mathematically adjusted to show what the pressure would be if your location were at sea level. This is called “mean sea level pressure,” and meteorologists use it so they can compare readings from a mountaintop station and a coastal city on equal terms. If you live at a higher elevation, your actual station pressure is lower than the adjusted number, but the adjusted figure is what matters for interpreting weather.
Reading Your Barometric Pressure
Barometric pressure in most inhabited areas ranges from about 980 to 1050 hPa (28.94 to 31.00 inHg). Where your current reading falls within that range tells you something useful:
- Above 1020 hPa (30.12 inHg): A high-pressure system is overhead. Expect generally clear skies, calm winds, and stable conditions. In winter, rising pressure often signals frost or cold, dry air.
- Around 1013 hPa (29.92 inHg): Conditions are near the standard baseline. Weather could go either way depending on whether pressure is trending up or down.
- Below 1000 hPa (29.53 inHg): A low-pressure system is nearby. This typically brings clouds, rain or snow, and stronger winds. The lower the reading, the more intense the storm system.
The trend matters more than any single number. A steady reading means current conditions will likely hold. A falling barometer signals incoming moisture and wind. A rising barometer points toward clearing skies, though if it rises very quickly after rain, the fair weather may not last long.
How Pressure Changes Predict Weather
NOAA’s historical forecasting guidelines still hold up remarkably well. When pressure drops gradually and stays low, expect extended wet weather within a day or two. A sudden, steep drop points to high winds, sometimes before rain even arrives. The lowest pressure readings of all tend to come when wind and rain hit simultaneously.
When pressure rises steadily during wet weather and holds, fair conditions typically follow within a day or two. But a sudden spike to very high pressure after a storm usually means the clear weather will be short-lived. In frosty conditions, rising pressure can signal snow rather than clearing.
If your barometer is bouncing up and down without settling, the weather will be equally unsettled. This instability often shows up during transitional seasons when competing air masses are moving through your area.
Why Your Body Feels Pressure Changes
If you’ve noticed that your joints ache or you get headaches when a storm rolls in, barometric pressure is a likely contributor. The connection is real, though the exact mechanism is still debated.
One theory involves the fluid inside your joints. When external air pressure drops, it may shift fluid dynamics within the joint, forcing lubricating fluid into areas rich with nerve endings in the bone just below the cartilage surface. This could reduce lubrication and simultaneously irritate sensitive tissue. Another explanation focuses on inflammation pathways: changes in pressure applied to cartilage cells trigger them to ramp up production of inflammatory signaling molecules, which can amplify pain perception even without visible swelling.
For migraines, the data is more specific. A study published in SpringerPlus found that migraine attacks occurred most frequently when atmospheric pressure dropped to between 1003 and 1007 hPa, roughly 6 to 10 hPa below the standard 1013 hPa baseline. Patients in that pressure window developed migraines at rates of 23 to 27 percent, significantly higher than control periods. So if you’re migraine-prone and you see your local pressure dipping into the low 1000s, that’s a window to be proactive with whatever management strategy works for you.
Pressure, Elevation, and Oxygen
Barometric pressure drops as you gain elevation, and that reduction has a direct effect on how much oxygen your blood can carry. At sea level, healthy adults typically have blood oxygen saturation around 96 to 99 percent. Research from the Tromsø study found that every 1 hPa drop in atmospheric pressure reduces oxygen saturation by about 0.006 percentage points. That’s negligible for day-to-day weather swings, which rarely shift more than 20 to 30 hPa.
The effect becomes meaningful at altitude. Climbing from near sea level to around 2,100 meters (roughly 6,900 feet) can lower blood oxygen saturation by about 4 percent. At 3,000 meters, healthy adults in one study averaged 90.2 percent saturation compared to their sea-level baseline. This is why you feel short of breath hiking in the mountains or flying in an unpressurized cabin. People with reduced lung function are more sensitive to these shifts, even at lower elevations.
Where to Check Pressure in Real Time
Several free tools give you accurate, location-specific readings. Weather Underground (wunderground.com) pulls data from a dense network of personal weather stations and displays current pressure with a trend arrow showing whether it’s rising or falling. The National Weather Service (weather.gov) provides pressure at your nearest official observation station. Most smartphone weather apps display barometric pressure if you scroll past the basic forecast, and some phones let you access the raw barometer sensor directly through a compass or altimeter app.
If you own a home weather station or a standalone barometer, keep in mind that your device shows station pressure, the actual air pressure at your elevation. To compare it with weather reports, you’ll need to apply a correction factor based on your altitude. Most digital home stations do this automatically once you enter your elevation during setup.