Barometric pressure · Below normal
1003 hPa.
1003 hPa is 10.25 hPa below standard — unsettled weather. Here is what the reading means, what it means rising, steady and falling, and how it converts across every scale your instruments might use.
Below normal
10.25 hPa below the 1013.25 hPa standard
what this reading means
The air mass overhead is lighter than standard — warm, moist, or lifting, or some combination of the three. This is the ordinary working pressure of active weather: not a dramatic storm, but an atmosphere that is doing something.
Clouds, showers, and the kind of gray, changeable day that a forecast summary struggles to describe. Frontal boundaries and the outer circulation of distant lows both live in this range.
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 1003 hPa carries three different forecasts.
Rising to 1003 hPa
Improvement in progress. Drying air is filtering in behind whatever just passed, and skies usually break within half a day.
Steady to 1003 hPa
An unsettled pattern that is going nowhere. Expect more of the same weather tomorrow: neither a clean clearing nor a genuine storm.
Falling to 1003 hPa
Something is approaching. A continued fall from this level, especially faster than 0.03 inHg (1 hPa) in three hours, is a dependable early warning that a front or low is on its way.
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:
1003 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.
29.62 inHg
inches of mercury — US weather apps
1003.0 hPa
hectopascals — the international standard
1003.0 mb
millibars — numerically identical to hPa
752.3 mmHg
millimetres of mercury
100.30 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 1003 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
This sits a measurable but unremarkable distance below the 29.92 inHg (1013.25 hPa) standard. The number alone will not tell you much here — the direction it is moving will.
Common. In much of the United States this band shows up on a meaningful share of days between autumn and spring.
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 1003 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 1003 hPa mean?
1003 hPa (29.62 inHg) is 10.25 hPa below the standard 1013.25 hPa, which classifies as below normal — unsettled weather. 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 improvement in progress. Falling, it means something is approaching.
Frequently Asked Questions
Is 1003 hPa high or low barometric pressure?
1003 hPa is below standard, by 10.25 hPa. Standard sea-level pressure is 29.92 inHg or 1013.25 hPa, and meteorologically this reading falls in the below normal band — unsettled weather. Common. In much of the United States this band shows up on a meaningful share of days between autumn and spring.
What is 1003 hPa in inHg?
1003 hPa equals 29.62 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 752.3 mmHg and 100.3 kPa.
What weather comes with 1003 hPa?
Clouds, showers, and the kind of gray, changeable day that a forecast summary struggles to describe. Frontal boundaries and the outer circulation of distant lows both live in this range. But the reading alone will not give you a forecast — the tendency will. Something is approaching. A continued fall from this level, especially faster than 0.03 inHg (1 hPa) in three hours, is a dependable early warning that a front or low is on its way.
Does 1003 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 1003 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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