March 2021 rainfall event

 

Between 14 March and 24 March 2021 was a period of rain and showers with some thunderstorms, as a result of an succession of favourable synoptic features. During this period a total of 263.3 mm was observed and was the wettest period since 364.9 mm was observed between the 3 February and 14 February 2020.

In the past 30 years the rainfall event total was the 14th highest on record and was in top 7 % of rain event totals. For March the rain event total was the second highest on record and the highest since the current record high of 278.2 mm between the 28 March and 31 March 2017 associated with Ex-Tropical Cyclone Debbie.

During this rainfall event a large portion of the rainfall occurred during the last few days of the event where 203.3 mm was measured between the 22 and 24 March. The highest 24 hour rainfall total was 129.7 mm on 22 March 2021 and for March this was the third highest 24 hour rainfall total observed on record and which was the highest since the current record high of 153.5 mm on 6 March 2004 (squally heavy rainfall between the 5 and 6 March 2004). When compared to all previous months the highest 24 hour rainfall total was the 21st highest on record and the highest since 143.4 mm on 24 February 2018 (showers becoming heavy rainfall on the 23 and 24 February).

At the time of writing the month-to-date total is 297 mm, which is 177.4 mm above the long term median and 248.3 % of the long term median. For March so far this is the highest March total rainfall since 375.4 mm in 2017, which is the current record high. However considering that showers are expected during the rest of the month the final total may end up as the second highest on record, due to the current second highest being 301.25 mm in 1992. For all months this is the highest since 389.2 mm in February 2020.

Year to date rainfall is currently 519 mm, which is 88 mm above the long term January to March total (16.9 % above average). This is lower than the January to March rainfall total in 2020, which saw both well above average rainfall in January and February in contrast to near average rainfall in 2021 until the above average rainfall in March 2021.

The number of rain days have been 51 so far this year (of least 0.2 mm of rainfall excluding daily rainfall totals that are entirely from dew, mist or fog). This is 16 days above the long term average, is the highest on record as compared with previous January to March totals since 52 days in 2015 and the third highest on record. For March this is the highest number of rain days since 18 days in March 2019.

Note that rainfall totals are based on manually recorded daily rainfall totals measured as the 24 hours to 9am. This data is currently not displayed on this website, except as contained in the weather reviews. Therefore there will be differences to the rainfall totals shown on the website that are collected automatically from a different rain gauge and is measured as the 24 hours from midnight.

Some charts from this period are below where daily data is for the 24 hours from midnight. This is based on the existing graphs on this website, but uses a script that allows to show data between a specific date range, rather than using data in the last x days. This alternate format is not available on the website at this time which could be included in a future update.

 

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