What Do Barometric Pressure Numbers Mean?

Tools

By By Steve Pool

SEATTLE - A barometer measures atmospheric pressure, which can help give you a rough idea of how the weather will be changing in the next 24 hours.

Sea-level barometer readings usually range from about 29.70 inches of mercury to 30.20 or so, with 29.92 being the average reading.

Pressure also drops with altitude too, so reported pressures are converted to sea-level to factor out the difference in altitude from individual reports. You can convert your observed pressure to sea-level by subtracting .06 inches for every 50 feet in altitude.

But it's not so much the actual number reading as the trend the readings are taking. A steadily falling barometer usually signals a storm is approaching, while a rising barometer normally means sunnier skies ahead. Although very low readings (under 29.50 inches) can suggest a strong storm approaching.

Your Photos

YouNews The Great Wheel The Great Wheel
Spent Thanksgiving with family and friends at Fisherman's on Pier 57.
YouNews Best Buy's Holiday Meals Best Buy's Holiday Meals
Every year Retail businesses go through the same event of working on Thanksgiving Day. But at least with that job, Corporate will offer a good meal to the employees that are told it is mandatory to work on that Holiday.
YouNews November 26th November 26th
Less than two weeks ago it was single digits here, probably made it into the low 40's the past few days. Lilac has new buds all over it and this one has started to grow.