Over the course of Sunday atmospheric pressure continued to build over the UK. In Eastbourne the e.brx.io weather station recorded a maximum of 1051.1hPa shortly before midnight. Pressure stayed high, above 1050 for the morning of 20 January, before beginning to decline back below that mark just after midday. It looks like the high is beginning to pass by.
Atmospheric pressure varies a lot, but rarely reaches such highs. The average pressure at sea level is 1013hPa, but high pressure systems are often only in the 1030s. Exceeding 1040hPa is remarkable. 1051.1hPa is comfortably the highest reading I have recorded in 8 years of operation, the yearly summary graph on my old website has a hard-coded maximum of 1050hPa, last night's readings were literally off the chart! The maximum recorded atmospheric pressure in the UK was 1053.6hPa at Aberdeen in 1902, according to the Met Office.
I should point out that my weather station has not been officially calibrated by anyone. I merely ensured that its readings were consistent with other local official readings when I installed the device, so readings are indicative only. I will be intrigued to discover what the Met Office decides is the official UK high from this system once it has gone.