Monthly sea level peak for May 2021

The lunar month’s highest tide occurred on 28th May 2021 for Waitemata harbour and 29th May Great Barrier Island.


The Waitemata harbour tidal gauge measured a mean level of 1.75 metres between 8:45pm and 9:00pm on 28th May which is 15cm above the May average (2015-2020). The barometric air pressure at the time of the reading was 1000.6 hPa, so when using the inverted barometric adjustment calculation method of 1cm for every 1 hPa, the projected height would have been 1.62 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 slightly downward. The tidal gauge data used for this analysis can be found here.



The Great Barrier Island tidal gauge measured a mean level of 1.34 metres between 9:30pm and 9:45pm on 29th May. The air pressure at the time of the reading was 992.2 hPa, so when using the inverted barometric adjustment calculation method of 1cm for every 1 hPa, the projected height would have been 1.13 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 slightly upward trend. The tidal gauge data used for this analysis can be found here.



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