People may not need their jumpers for long as the day is set to warm up to around 18C in most places.
O’Connor said some parts of Northland may see temperatures reach the low 20s during the day later this week but the nights could stay cold.
MetService’s outlook for the coming month said the hallmark of El Niño in New Zealand is a cold spring, which appears to be the case for October.
“Expect a colder than average October across the country, with the exception of Nelson, Marlborough, Canterbury, Gisborne and Hawke’s Bay.”
For the last week of the school holidays, a high brings a relatively dry week but the rest of the month will see a stronger than normal ridge over Northland.
“In between, stronger than usual westerlies are forecast – it looks likely to be a windier than normal October.”
Below-normal rainfall is also predicted for Northland.
The bottom line: “A colder and windier than usual October is forecast for many regions.”
However, last month bucked the trend as the country recorded the hottest September on record since records began in 1909.
According to the Niwa Climate Summary for September, the average temperature nationwide was 11.9C - 1.3C above the 1991-2020 September average.
Niwa Climate Scientist Gregor Macara said high-pressure weather systems were most prevalent over the country during the first half of the month, delivering a period of relatively benign weather for many areas.
The second half of September became more unsettled, with several frontal systems contributing to very strong westerly and northwesterly wind events.
By September’s end, Macara said an El Niño event was declared and the climate driver was a likely contributor to the persistent westerly and northwesterly winds observed during the latter half of the month.
In the Far North, Kaikohe recorded its highest September temperature since 1973 with 23.5C on September 20. That same day Kerikeri recorded its second highest September temperature since 1945 with 24.2C.
However, the highest September temperature was 29.6C at Wairoa on September 21. The lowest September temperature was -5.9°C, observed at Mount Cook Airport on September 26.