Monday rain tips 2023 into Gisborne's wettest year on record

A stormfront moves in over Gisborne earlier his month. File picture by Liam Clayton

This year has become Gisborne’s wettest on record, since official weather data was collected at Darton Airfield from 1937.

Monday night’s rain saw 3.9 millimetres delivered to the airport rain gauge — enough to break the 86-year-old record.

Those few millimetres brought the total for year to date to 1434.5mm.

Gisborne’s previous wettest year, as measured at the airport, was back in 1938, when the full year totalled 1432.3mm.

With four and a half months still to go to the end of the year, the new record total will obviously be higher still.

The latest 30-year set of averages, for 1991 to 2020, puts Gisborne’s mean annual rainfall at 999.8 millimetres.

The year’s average rainfall was exceeded in June — in just half a year.

It remains to be seen if the end-of-year total reaches the unofficial figures recorded by a rain gauge at the port.

More than a century ago, in 1879, the harbour gauge measured a total of 1634mm.

In the next 10 years or so, it recorded two more years that were close to 1600mm for their 12 months.

That it has been wet is beyond argument — the daily climate charts of the National Institute of Water and Atmospheric Research show most of the district is still at or close to soil moisture capacity.

In many areas around the flats, the groundwater level is just below the soil surface.

Gisborne could set another weather record this year as a result of all the cloud and rain.

It could be the gloomiest year on the books, with sunshine hours well down on the norm.

To the end of July MetService recorded just over 1085 hours of sunshine at the airport, with March the only month that enjoyed more sun than usual.

So far, the year is running about 150 hours short of the sunshine it should have received.