NIWA

Climate Summary for April 2023

3 May 2023

Dry and warm for many parts of the country

Rainfall	Below normal (50-79% of normal) or well below normal (<50% of normal) rainfall was common for Southland, coastal Otago, Canterbury, inland Manawatū-Whanganui, Hawke’s Bay, Bay of Plenty, Waikato, and parts of Auckland. Rainfall was above normal (120-149% of normal) or well above normal (>149% of normal) for Central Otago, parts of the West Coast, Nelson, northern Tasman, Wellington, Kāpiti Coast, Wairarapa, inland Taranaki, and parts of Northland.
Temperature	Temperatures were above average (0.51-1.20°C above average) or well above average (>1.20°C above average) across most of the country, except for small areas of near average (±0.50°C of average) temperatures in parts of Central Otago.
Soil Moisture	At the end of April, soil moisture levels were above normal for parts of Northland, western Bay of Plenty, coastal Gisborne, much of the lower North Island, northern Canterbury, Banks Peninsula, and southern parts of the Mackenzie Basin. Meanwhile, below normal soil moisture levels were present in coastal parts of North Otago and South Canterbury. Elsewhere, soil moisture levels were generally near normal.

Overview

April 2023 was a dry and warm month for many parts of Aotearoa New Zealand with plenty of sunshine for the lower and western South Island. Mean sea level pressure (MSLP) was lower than normal over and northwest of the country, and higher than normal east and southeast of the country. This MSLP pattern resulted in more northeasterly winds than normal over New Zealand. ENSO-neutral conditions persisted in April, however seas continued to warm across the equatorial Pacific, consistent with a developing El Niño. Sea surface temperatures (SSTs) remained above average during April near the western North Island and around the South Island, with near average SSTs near the northern and eastern North Island.

It was a relatively dry month for many parts of the country, and below normal (50-79% of normal) or well below normal rainfall (<50% of normal) was widespread for both the North and South Islands. Napier received just 28% of its normal April rainfall – a welcome reprieve after a very wet start to the year. Occasional periods of unsettled weather delivered heavy rainfalls to some parts of the country, with April rainfall totals above normal (120-149% of normal) or well above normal (>149% of normal) for Central Otago, parts of the West Coast, Nelson, northern Tasman, Wellington, Kāpiti Coast, Wairarapa, inland Taranaki, and parts of Northland. Atmospheric instability resulted in several areas of strong convective activity and the development of thunderstorms, with five tornadoes reported across New Zealand during the month (see Highlights and extreme events section for further details).

The prevalence of elevated SSTs near New Zealand and more northeasterly winds than normal resulted in a warm month overall. Temperatures were above average (0.51-1.20°C above average) or well above average (>1.20°C above average) across most of the country. The exception was parts of Central Otago where temperatures were near average (±0.50°C of average). The nationwide average temperature in April 2023 was 14.4°C. This was 1.1°C above the 1991-2020 April average from NIWA’s seven station temperature series which begins in 1909, and New Zealand’s 11th-warmest April on record.

Further Highlights:

The highest temperature was 27.5°C, observed at Wairoa on 20 April.
The lowest temperature was -4.1°C, observed at Pukaki Aerodrome on 25 April.
The highest 1-day rainfall was 134 mm, recorded at Pukeiti (Taranaki) on 21 April.
The highest wind gust was 193 km/h, observed at Cape Turnagain on 26 April.
Of the six main centres in April 2023, Auckland was the warmest and least sunny, Dunedin was the driest and coolest, Wellington was the wettest, and Tauranga was the sunniest.
Of the available, regularly reporting sunshine observation sites, the sunniest four locations so far in 2023 are Central Otago (981 hours), West Coast (972 hours), Taranaki (964 hours), and Mackenzie Basin (957 hours).