What October did to the weather

RAIN: We still need more. The flood was in September, and only one decent delivery of rain in October has left us short of the monthly average. File picture

A SHIFT in the weather over October has made a big difference to the Gisborne district’s climate picture, except in the one crucial area of rainfall.

Just one decent delivery of rain of rain over October topped up the soaking of September, but still fell short of the average for the month.

October ended with 41mm of rain - down on the 30-year average of just over 72mm.

As a result of another dry month, the Gisborne area’s rainfall for the year to date stands at around 780mm, some 200mm short of last year’s 980mm to the end of October, and 100mm down on the 30-year average.

By the end of the month the running rainfall deficit for Gisborne had risen to 64mm.

Evapotranspiration rates (the loss of moisture from the soil) rose, pumped up by a significant swing in wind direction to the northwest, and longer, sunnier days resulting from clear skies.

The lack of cloud and rain saw a dramatic rise in sunshine hours, with more than 265 hours compared to the 30-year average of just under 180 hours.

Despite the big dose of sunshine, it still fell short of the 1972 record, which experienced 285 hours of sun that October.

Thanks to the sun, the north-westers and the drying fohn effect, daytime temperatures finally rose significantly.

Above the 30-year averageThe mean daily maximum reached 20.4 degrees, about a degree-and-a-half above the 30-year average.

Top temperature for the month was 27.9 degrees, well short of the 30.8 degree record set for October in 1977.

Despite the daytime warmth, night and early morning temperatures remained stubbornly low, chilling pasture growth.

There were six mornings of below-zero grass temperatures, well above the 30-year average of one ground frost for the month of October.

The coldest morning was the 10th with a grass minimum of minus 2.5 and an air temperature of just 2.3.

On top of the six below-zero grass minimums, there were another five mornings when the grass minimum fell below two degrees.

Nevertheless, the mean minimum air temperature for the month was a whisker over the 30-year average at nine degrees.

The most significant change over the month was in the wind, with a huge swing from preceding months where southerlies have had a big cooling effect.

Over October northwest winds became dominant, with 19 days of warming winds from that quarter compared to six days of southerlies, two days of south-easterlies and one day of an easterly.

The strongest gust of the month was a nor’wester which topped the 61kmh mark on the 13th.