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Monthly sea level peak for September 2021

The lunar month’s highest tide occurred on 10th September for Waitemata harbour and Great Barrier Island.


The Waitemata harbour tidal gauge measured a mean level of 1.68 metres between 10:00pm and 10:15pm on 10th September which is 6cmm below the September average (2015-2020). The barometric air pressure at the time of the reading was 1004.2 hPa, so when using the inverted barometric adjustment calculation method of 1cm for every 1 hPa, the projected height would have been 1.59 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 1.30 metres between 9:15pm and 9:30pm on 10th September which is 9cm above the September average (2015-2020). The air pressure at the time of the reading was 1004.2 hPa, so when using the inverted barometric adjustment calculation method of 1cm for every 1 hPa, the projected height would have been 1.21 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 slightly upward. The tidal gauge data used for this analysis can be found here.



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