Barometric pressure today

It is the weight of the air above you, pressing down on everything at ground level. Air is always on the move, so sometimes more of it piles up overhead and the reading rises, and sometimes it drains away and the reading falls. That is why the number changes from one day to the next.

It depends where you are. The card at the top of this page shows your own city when we can tell where you are: the reading now, which way it is going and how far it has moved since yesterday. If we could not, search for your city at the top. The lists further up show where pressure is falling and rising fastest right now.

Near 1013 hPa at sea level; the exact standard figure, 1013.25 hPa, is the same as 760 mmHg, 29.92 inHg or 101.3 kPa. Most days sit between about 1000 and 1025 hPa. Storms over Europe and North America can take it below 980, and a strong settled high can push it above 1035. Which way the number is going usually tells you more than the number itself.

At sea level anything between about 1000 and 1025 hPa is ordinary, so 1017 hPa is an ordinary day on the high side and 1005 hPa an ordinary day on the low side. Below 1000 hPa is low, and a deep storm goes under 980; above 1025 is high, and a strong settled high goes past 1035. In inches of mercury the ordinary band runs from about 29.5 to 30.3 inHg, so 29.79 inHg is ordinary too. Every city page answers this for its own reading, and the cities we have several years of figures for also say what is usual there.

Not on its own. Away from the tropics, a fall usually means a low is heading your way, and lows carry the fronts that bring cloud, wind and rain, so the two often arrive together. But a shallow fall can pass with nothing more than cloud, and rain falls under steady pressure too. Each city page puts the rain forecast next to the pressure, so you can see both.

Usually altitude. Weather services correct readings to what they would be at sea level, so that cities can be compared with each other. A barometer in your room reads the air where it actually stands. Close to sea level that is roughly 1 hPa lower for every 8 to 9 metres you go up, and higher up each extra metre counts for a little less, so every city page works the figure out for that city instead of using a rule of thumb. Each page has a switch for both readings and always says which one you are looking at.

Yes, exactly the same amount of pressure. The name changed, the number did not, so 1013 mbar and 1013 hPa mean the same thing. You can also read the same figure in millimetres of mercury, inches of mercury or kilopascals here.

Multiply by 0.75, so 1013 hPa is 760 mmHg. For inches of mercury, divide by 33.86: standard sea-level pressure, 1013.25 hPa, is the familiar 29.92 inHg. For kilopascals, divide by 10. The switch at the top of every page does all of this for you.

Seven days ahead everywhere, and the past week or more behind, on one graph. The days behind you are the model's record of each hour as it passed, anchored to real observations, though still not a reading from an instrument in your street, and every page says so.

The forecast comes from the ECMWF model, run by the European Centre for Medium-Range Weather Forecasts, and reaches us through Open-Meteo. The model publishes four times a day, and we pick up each new run within half an hour of it landing.