Monthly sea level peak for August 2021

Updated: Sep 29, 2021

The lunar month’s highest tide occurred on 13th August for Waitemata harbour and 22nd August for Great Barrier Island.


The Waitemata harbour tidal gauge measured a mean level of 1.38 metres between 10:45pm and 11:00pm on 13th August which is 33cm below the August average (2015-2020). The barometric air pressure at the time of the reading was 1017.2 hPa, so when using the inverted barometric adjustment calculation method of 1cm for every 1 hPa, the projected height would have been 1.42 metres at the mean sea level pressure of 1013 hPa. More on meteorological effects on tides can be found here.


The ongoing trend between 2014 to 2021 for the Waitemata harbour sea level peak is downward. The tidal gauge data used for this analysis can be found here.


The Great Barrier Island tidal gauge measured a mean level of 1.18 metres between 7:15pm and 7:30pm on 22nd August which is 2cm below the August average (2015-2020). The air pressure at the time of the reading was 1030.4 hPa, so when using the inverted barometric adjustment calculation method of 1cm for every 1 hPa, the projected height would have been 1.35 metres at the mean sea level pressure of 1013 hPa. More on meteorological effects on tides can be found here.


The ongoing trend between 2014 to 2021 for Great Barrier Island sea level peak is a flat. The tidal gauge data used for this analysis can be found here.



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