Barometric pressure · Very low
971 hPa.
971 hPa is 42.25 hPa below standard — deep-storm pressure. Here is what the reading means, what it means rising, steady and falling, and how it converts across every scale your instruments might use.
Very low
42.25 hPa below the 1013.25 hPa standard
what this reading means
A powerful, fully developed low-pressure center is at or very near the station. Air is converging at the surface and rising through a deep layer of the atmosphere, which is why storms at this pressure produce rain over a wide area rather than in isolated cells.
Heavy, persistent precipitation and strong wind across a broad footprint. On the US East Coast this is classic nor easter territory; in the Gulf and Atlantic it is a landfalling tropical system; in the Midwest it can be an inland cyclone strong enough to produce a wind event without a thunderstorm.
the number is half the signal
A barometer reading on its own is a snapshot of a system in motion. Forecasters read the tendency — which direction the value has moved over the last three hours — because that is what distinguishes weather arriving from weather leaving. The same 971 hPa carries three different forecasts.
Rising to 971 hPa
The center has passed or is filling. Expect the wind to shift direction as the low moves off, then gradually ease. Clearing usually lags the pressure rise by several hours.
Steady to 971 hPa
The storm is neither strengthening nor weakening, and it is not moving quickly. A stalled deep low is how a wind and rain event turns into a flooding event.
Falling to 971 hPa
Continued deepening. A drop of more than 0.07 inHg (2.5 hPa) in three hours at this level indicates a storm still organizing, and the peak wind has not arrived yet.
how fast it is moving
Rate matters more than direction. Weather services report pressure tendency over a three-hour window, and these are the thresholds that change what a forecaster says:
971 hPa in every scale
All five of these are the same pressure. US weather apps default to inches of mercury, a holdover from seventeenth-century mercury-column barometers; almost everywhere else uses hectopascals, and aviation and marine instruments often use millibars, which are numerically identical to hPa.
28.67 inHg
inches of mercury — US weather apps
971.0 hPa
hectopascals — the international standard
971.0 mb
millibars — numerically identical to hPa
728.3 mmHg
millimetres of mercury
97.10 kPa
kilopascals
why your altitude does not change this number
The pressure your weather app shows is sea-level adjusted — the value your station would read if it were at sea level. It has to be, or the map would be useless: real station pressure in Denver runs near 24.8 inHg simply because there is a mile less atmosphere overhead, and every mountain station would look like a permanent hurricane.
So 971 hPa means the same thing in Denver as it does in Miami. If you own a barometer that reads noticeably lower than your weather app, it is almost certainly reporting raw station pressure and needs to be set to your elevation.
where this sits on the scale
The lowest non-tropical pressure ever recorded in the continental United States was 955.2 hPa (28.21 inHg), over Minnesota on 26 October 2010 — so a reading in this band sits within striking distance of the strongest storms the continent produces.
Rare. Most US stations see pressure this low only during a named storm or a once-in-several-years extratropical cyclone.
pressure and how you feel
Headaches, migraines, and aching joints are widely reported around pressure changes, and the research finds a real but inconsistent association — most often with falling pressure rather than with any particular value. A barometer sitting steadily at 971 hPa is a much less likely trigger than a fast drop toward it.
If your symptoms genuinely track the weather, the number to watch is the three-hour change, not the level. This is general information about atmospheric pressure, not medical advice.
nearby readings
For the physics underneath all of this — why rising pressure suppresses cloud and falling pressure builds it — read barometric pressure explained, or see how to read a surface pressure map. The full index of readings is at the pressure reference.
What does a barometric pressure of 971 hPa mean?
971 hPa (28.67 inHg) is 42.25 hPa below the standard 1013.25 hPa, which classifies as very low — deep-storm pressure. On its own the number is only half the signal: the band tells you the regime, and the direction of change tells you the forecast. Rising, it means the center has passed or is filling. Falling, it means continued deepening.
Frequently Asked Questions
Is 971 hPa high or low barometric pressure?
971 hPa is below standard, by 42.25 hPa. Standard sea-level pressure is 29.92 inHg or 1013.25 hPa, and meteorologically this reading falls in the very low band — deep-storm pressure. Rare. Most US stations see pressure this low only during a named storm or a once-in-several-years extratropical cyclone.
What is 971 hPa in inHg?
971 hPa equals 28.67 inHg. The two scales measure the same thing: 1 inHg is 33.8639 hPa, so to convert inHg to hPa multiply by 33.8639, and to convert hPa to inHg multiply by 0.02953. The same reading is also 728.3 mmHg and 97.1 kPa.
What weather comes with 971 hPa?
Heavy, persistent precipitation and strong wind across a broad footprint. On the US East Coast this is classic nor easter territory; in the Gulf and Atlantic it is a landfalling tropical system; in the Midwest it can be an inland cyclone strong enough to produce a wind event without a thunderstorm. But the reading alone will not give you a forecast — the tendency will. Continued deepening. A drop of more than 0.07 inHg (2.5 hPa) in three hours at this level indicates a storm still organizing, and the peak wind has not arrived yet.
Does 971 hPa cause headaches?
Many people report headaches, migraines, and joint pain around pressure changes, and the research finds a real but inconsistent association — most often with falling pressure rather than with any particular value. A steady reading of 971 hPa is far less likely to be the trigger than a rapid drop toward it. If symptoms track your barometer, the rate of change is the number to watch, not the level.
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