Monthly sea level peak for July 2021

The lunar month’s highest tide occurred on 25th July for Waitemata harbour and 22nd July for Great Barrier Island.


The Waitemata harbour tidal gauge measured a mean level of 1.63 metres between 8:15pm and 8:30pm on 25th July which is 9cm below the July average (2015-2020). The barometric air pressure at the time of the reading was 1013.2 hPa, so when using the inverted barometric adjustment calculation method of 1cm for every 1 hPa, the projected height would have been 1.63 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 1.13 metres between 5:15pm and 5:30pm on 22nd July which is 6cm below the July average (2015-2020). The air pressure at the time of the reading was 1005.2 hPa, so when using the inverted barometric adjustment calculation method of 1cm for every 1 hPa, the projected height would have been 1.20 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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