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What is normal barometric pressure?

Normal sea-level barometric pressure is roughly 29.68–30.12 inHg (1005–1020 hPa), centered on the standard atmosphere of 29.92 inHg (1013.25 hPa). A reading of 30.00 inHg (1015.9 hPa) is normal — slightly above standard, not high.

Two conditions sit behind that answer. The range is a convention, not a law of nature, and it only applies to sea-level-reduced readings — a raw barometer at altitude will read far lower. Both are covered below, along with what fifty US cities actually average and how far outside the band real pressure goes.

The reference point: 29.92 inHg

The one fixed number in all of this is the standard atmosphere. NOAA’s JetStream guide puts standard sea-level pressure at 29.92 inHg, which is 1013.25 hPa — the same figure in millibars, since 1 hPa = 1 mb. In other units it is 760 mmHg, 101,325 Pa or 14.696 psi.

That is a defined reference value, the starting point of the International and US Standard Atmosphere models. It is not a prediction of what your barometer will say on a given day, and real pressure is almost never exactly 29.92. “Normal” has to be a range around it.

The normal range, and the zones around it

This site reads every pressure value against five fixed pressure zones, defined in sea-level hPa and identical for every city. Converted at the site’s factor of 1 hPa = 0.02953 inHg:

So 30.00 inHg is normal, 0.08 inHg (about 2.7 hPa) above standard and 0.12 inHg short of the high zone. 30.12 inHg is the line where “high” begins on this scale.

These cut points are interpretive conventions, and other sources draw them differently. Pressure Pal, for instance, gives a practical range of about 29.80 to 30.20 inHg (about 1009 to 1023 mb), and other published ranges sit nearby but not on top of each other. None of them is a standard. What this site guarantees is that its boundaries are the same on every page, so a value 0.01 inHg either side of a line is a rounding difference, not a change in the weather. If you came with one specific reading, the 29.95 inHg article has a lookup table from 29.50 to 30.50 inHg.

Average vs. normal: what 50 US cities actually show

“Average barometric pressure” has a more concrete answer than “normal”, because it can be measured. Across the ten years of Open-Meteo ERA5 hourly reanalysis behind this site’s 50 city pages (2015–2024), every city’s mean sea-level pressure falls between 29.89 inHg (1012.3 hPa) and 30.08 inHg (1018.5 hPa). All fifty sit inside the normal band.

The four highest and two lowest ten-year means of the 50 cities. Sea-level-reduced; Open-Meteo ERA5 hourly reanalysis, 2015–2024.

That spread is about 6 hPa (0.18 inHg) from top to bottom — narrower than the normal band itself. So the honest picture is a very tight center near standard, with day-to-day weather moving around it. Atlanta’s higher mean does not make Atlanta a “high-pressure city” in any felt sense; it is still a normal-band average.

Normal is also where most hours are spent, not just where averages land. In Miami, the calmest city in the set, 90% of hours fall between 29.87 inHg (1011.5 hPa) and 30.21 inHg (1023.0 hPa). Phoenix has the lowest average, and even its 5th percentile, 29.67 inHg (1004.7 hPa), sits only a fraction under the low boundary.

Is there a “good” barometric pressure?

No. There is no good or bad level, and this site does not treat any reading as healthier than another. High pressure tends to come with settled weather and low pressure with unsettled weather, but neither is healthier as a number.

For pressure-sensitive people, the thing commonly reported is change, not level. As the methodology sets out, studies have repeatedly found a statistical association between barometric pressure change and migraine onset in some people, and no association in others; effect sizes are modest and individual sensitivity varies widely. That is why the city pages count swing days — days with a 24-hour change of at least 0.18 inHg (6 hPa) — rather than flagging any particular reading. A steady 29.70 inHg (1005.8 hPa) is a quieter day, in that sense, than 30.10 inHg (1019.3 hPa) falling fast.

The sea-level vs. station trap

Every number above is sea-level-reduced pressure — what weather reports quote, and what the zones are drawn for. A barometer showing raw station pressure reads lower, and the gap grows with altitude. At altitude, a station reading will sit below every band on the scale and look “very low” when nothing unusual is happening.

The size of the gap is easy to underestimate. In Denver, at 1,615 m, the ten-year mean sea-level pressure is 29.97 inHg (1014.8 hPa) and the mean station pressure is 24.74 inHg (837.7 hPa) — about 5.23 inHg (177 hPa) lower. In Phoenix, at 333 m, the gap is about 1.12 inHg (38 hPa): station pressure averages 28.77 inHg (974.4 hPa). In Miami, at 6 m, the two figures differ by under 1 hPa.

The test is simple. If you live well above sea level and your device shows something near 29.9 or 30.0 inHg (roughly 1012–1016 hPa), it has been corrected to sea level and this article applies. If it shows something far lower, it is displaying station pressure. Each city page lists its mean station pressure next to the sea-level figures so you can tell which one your device matches; for a town that is not one of the 50, use the location lookup.

How far outside normal pressure actually goes

Leaving the normal band is routine; leaving it by a lot is rare. The single highest and lowest hourly sea-level values in five cities’ ten-year records show the real envelope:

Record highs land between 30.50 and 31.16 inHg (1032.9–1055.2 hPa), all in the very-high zone. Record lows run from 29.43 inHg (996.7 hPa) in Phoenix down to 28.66 inHg (970.7 hPa) in Boston, during a February 2020 nor’easter. Miami’s low came with Hurricane Irma. These are one-hour extremes across ten years, not ordinary weather — real, but rare.

Denver’s record high comes with a caveat. Sea-level reduction at altitude inflates apparent variability, which is part of why high-elevation cities top the volatility rankings — Salt Lake City (1,302 m) has the highest pressure variability of the 50 (standard deviation 0.26 inHg, 8.64 hPa); Denver ranks fifth. Treat Denver’s extremes as less directly comparable to Miami’s or Boston’s.

What “normal” does not tell you

All the city figures come from Open-Meteo ERA5 hourly reanalysis for 2015–2024 — a model reconstruction constrained by observations, taken at each city’s centroid, not a single station’s barograph. Ten years describes typical behavior well but supports no trend claims. And a normal reading says nothing about where pressure is heading; for that, the live chart and outlook calendar on any of the 50 city pages are the place to look.

Pressure change has been statistically associated with migraine onset in some people and not in others; effect sizes are modest and individual sensitivity varies widely. Nothing on this page predicts a headache, diagnoses anything, or is medical advice. If migraine is affecting your life, that is a conversation for a clinician.

All 50 city pages · Check any US location · Methodology