Barometric pressure by ZIP code
What the number means
Barometric pressure is the weight of the air above you. Weather stations and forecasts usually show it in inches of mercury (inHg) in the U.S. and in hectopascals (hPa) or millibars (mb) elsewhere; 1 hPa is the same as 1 mb. Average pressure at sea level is 29.92 inHg, or 1013.25 hPa.
These ranges are a rough guide of our own, not an official scale. The trend matters more than the exact number: a falling barometer usually tells you more than a "low" one.
Rising or falling: reading the trend
The calculator compares the latest reading with the one from about 3 hours earlier, the time span forecasters use for the pressure tendency. Our simple labels: a change of less than 1 hPa is "steady", 1 to 3 hPa is "rising" or "falling", and more than 3 hPa in 3 hours is "fast". These labels are our own summary to help you read the chart, not an NWS product.
Why it matters: high pressure systems are sinking air, which tends to dry things out. Low pressure systems are rising air, which builds clouds and storms. Our page what is barometric pressure? explains this in more detail.
Why your home barometer may read differently
- Sea-level vs station pressure: pressure drops as you go higher. Forecasts and most weather stations show pressure corrected to sea level, so towns at different heights can be compared. A barometer that is not set for your elevation will read too low in high places.
- Distance: the nearest NWS station may be miles away, often at an airport. Pressure changes slowly over distance, so the difference is usually small, but not zero.
- Units: need the number in another unit? Use our barometric pressure converter.
Want your own live readings, also for your exact backyard? Many home weather stations have a built-in barometer and a pressure graph. Our weather station quiz helps you pick one.
Quick answers
What is a normal barometric pressure?
The standard average at sea level is 29.92 inHg (1013.25 hPa). Day-to-day readings commonly move a few tenths of an inch above or below that.
Where does this data come from?
From the public National Weather Service API (api.weather.gov): the observation stations nearest to your ZIP code. The ZIP code location comes from the U.S. Census Bureau's ZIP Code Tabulation Areas.
Why does it say no recent reading?
Some stations do not report pressure every hour, and readings older than 3 hours are not shown. The tool then tries the next nearest stations; if none of them has a recent reading, try again later.
Does it work outside the U.S.?
No. It uses U.S. ZIP codes and National Weather Service stations only.
Sources: National Weather Service API · U.S. Census Bureau: Gazetteer Files (ZCTA) · NWS El Paso: pressure conversion
