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On-line barograph

Atmospheric pressure in Teddington: 1025.4 hPa
Sea-level equivalent: 1026.4 hPa
Three hour trend: +1.5 hPa
Time of measurement - made every 5 minutes (see note about UTC below): 20:05 UTC
Date: 2014/Sep/21

There is no need to tap the screen.....

The graphs below show the pressure in Teddington for the past 24 hours and 7 days.

The barometric pressure data is derived from an on-line electronic pressure transducer. The measurement uncertainty of this on-line transducer is approximately 0.3 hPa. The unit hectopascal (hPa) is numerically identical to the millibar (mbar) Link to pressure units.

The pressure values shown are those at the point of measurement, that is approximately 10 metres above mean sea level. If a hole were dug to sea level, the pressure at the bottom would be about 1 hPa greater than at the top. Note that, when estimating a pressure value from the graphs, the uncertainty will be considerably higher than that of the measuring transducer because of limitations in screen resolution.

When using the pressure values, particularly for checking another barometer, it is important to appreciate that the differences in altitude, distance from Teddington and weather conditions may seriously limit the validity of the comparison.

Proper calibration of barometers can only be accomplished by direct pneumatic connection to an appropriate pressure standard and adherence to well defined procedures.

For the latest weather forecast, see the Met Office

Historical Barometric Pressure Data

View historical barometric pressure data, going back until 1st January 1998, when the on-line barograph was first set up (excluding an eleven day period starting 09/08/02*).

To plot the pressure graph select desired start and end dates and click OK

Start:  

End:  

The historical barometric pressure data is derived from records starting 1st January 1998, (before 2nd April 2001 only an hourly average value was stored, so graphs relating to the earlier data therefore show slightly less fine-structure than measurements made after that date). The measurement uncertainty associated with each individual 5-minute measurement is 0.3 hPa but the hourly averaging of the pre-2nd April 2001 data effectively increased the uncertainty by an amount which depended on the rate-of-change of pressure during the hour in question.

*Due to a computer failure no data was recorded during an eleven day period starting on 9 August 2002. Please note that the graph plotting software used to display the historical barometric pressure data was designed to linearly interpolate (ie draw a straight line) between successive data points. Unfortunately this means that, should you elect to display a period that includes both 9 August and 20 August, the software will erroneously draw a straight line from the last data point recorded on 9 August to the first data point recorded on 20 August. This line probably bears no resemblance to real atmospheric pressure variations during the breakdown period.