Eyes on low rainfall trend

A109 Light Utility Helicopter flight with mayor Gisborne City from the air in November 2023.

As some may know, I do regular analysis of weather data provided by our weather agencies.

Farmers and gardeners may be interested to know where we are at heading towards summer.

The latest figures show Gisborne has now had five months in a row of below-average rainfall.

As at the end of September, rainfall for the year stood at just over 550mm — almost 350mm short of what Gisborne had received at the same time last year.

The rain total for September was just 38.5mm — about half the 30-year average of 73.5mm.

The daily climate maps produced by Niwa show a drier-than-normal area covering the Gisborne flats and coastal country up to Tolaga Bay.

However, soil moisture ?levels are still satisfactory and the current deficit is only around 50mm.

Temperature-wise, September broke the year’s run of above-average temperatures, as a result of some chill southerly weather and cloudless nights.

Overall the monthly mean daily temperature was around 11.5 degrees — about half a degree cooler than usual. Not only was it the first month of the year to be below-average warmth, but it was also only the second month with below-average sunshine.

Despite the passing of the spring equinox, Gisborne’s regular equinoctial northwesters have yet to kick in, apart from one five-day burst in mid-September.

The official outlook for the next three months is for rain, temperatures, soil moisture and river flows all to be about normal, but it would be wise to keep an eye on the year’s ongoing low rainfall trend.

Roger Handford