Autumnal nip likely as equinox approaches

The Oceanic Nino Index from 1992 to the present. The major El Niño and La Niña events are the orange and blue humps and dips.

The next few days are forecast to bring the first touches of autumnal weather to Gisborne and the East Coast, with lower temperatures and southerly winds.

Not much rain is in the offing — a bit over five millimetres yesterday — and March has so far had a total of less than 10mm of moisture.

Nothing dramatic is in the MetService outlook for the weekend and next week, but what some are calling a “polar blast” is slated to hit folk in the bottom half of the South Island, with the possibility of some snow.

Although the temperature drop in the coming days will not be bone-chilling, it might be felt after the warmth of Thursday night and Friday morning, when it was a toasty 19.5 degrees at 3am.

The coldest snap of this year so far was earlier this month on the 6th and 7th. On the morning of the 7th the air temperature dropped to 7.5, and the grass minimum temperature hit a frosty 1.9 degrees.

Tonight overnight temperatures are expected to drop to around seven degrees, while MetService says Tuesday and Wednesday will see daytime maximums fall to 17 or 18, and overnight minimums down to 10 degrees.

Next Thursday is forecast to have a maximum of 21 and a night-time low of eight.

It will be a case of “four seasons in one day”  through to next Thursday, with strong southerly winds  in the mix for Saturday and again mid-week.

With the autumnal equinox at 4.06pm next Wednesday, many residents will be asking if we really had much of a summer.

While the summer months of December to February’s end were certainly a mixed bag, the weather data shows it was actually warmer than usual, particularly over the nights.

The daily maximums averaged 24.8 degrees over the three months — a degree warmer than the 30-year mean. The overnight minimums averaged 14.9 — 1.2 degrees warmer than the 30-year average.

After Gisborne’s third-wettest November on record, December, February and this month to date have all been dry.

Despite the relief of rain in January, the soil moisture deficit is now back up over 120mm.

The 30-year average rainfall for the first three months of the year is 227mm, but so far the district has had under 150mm.

The latest guidance from the major climate agencies in the US is that El Niño continues to weaken, but is still quite strong — as indicated by the Marlborough region’s drought.