Preliminary analysis by NIWA climate scientists has shown that the recent Canterbury rainfall was so extreme in some inland places that it could be expected to happen only once every 200 years.
As of 24 March, the New Zealand Drought Index (NZDI) map below shows that widespread dry to very dry conditions extend from southern Northland to Wellington, excluding Taranaki, and across the east of the North Island, as well as Marlborough, eastern and coastal Canterbury, parts of Otago and Southland.
The New Zealand Drought Index (NZDI) map below shows that meteorological drought is in place in a very small portion of East Cape, while widespread dry-to-extremely dry conditions are in place across nearly all of the North Island, excluding parts of Northland, Coromandel and Taranaki.
Hotspots are currently in place in much of Northland, parts of Auckland, northern Waikato and a small portion of East Cape, while hotspots have strengthened in eastern Wairarapa and expanded to include the eastern Tararua District and coastal Hawke’s Bay. The New Zealand Drought Index (NZDI) map below shows that meteorological drought and severe meteorological drought are in place in the northern half of the Far North District.
Soil moisture decreases were observed across most of the North Island during the past week, with the most substantial losses occurring from lower Northland through to Bay of Plenty and East Cape.
However, most locations in the upper and central North Island will likely see either little change or small decreases in soil moisture levels during the next week.
In the North Island, many locations received moderate to substantial rainfall amounts ranging between about 30-60 mm, including much of Northland, Waikato, Taranaki, Gisborne, and Hawke’s Bay. Meanwhile, amounts less than 30 mm were observed across eastern Northland, Auckland, Manawatu-Whanganui, and Wairarapa.
Meanwhile, the wettest soils for this time of the year are located from Manawatu-Whanganui to Hawke’s Bay. Despite the general drying of soils during the past week, no hotspots are currently found across the North Island.
Many parts of the South Island saw small soil moisture increases during the past week, although small decreases were observed in northern Canterbury.While soil moisture increases will be possible in the lower South Island during the next week, expect further decreases across Marlborough and Canterbury.
With the anticipated rainfall in the upcoming week, little or no change in soil moisture levels are expected from the south Waikato northbound, along with parts of southern Hawke’s Bay and coastal Wairarapa, while the rest of the North Island are expected to experience slight soil moisture increases.
Across the North Island, moderate to large increases in soil moisture levels were observed in most locations due to substantial rainfall in the past week.
Due to the anticipated below normal rainfall and above average temperatures in the next week, soil moisture levels are expected to decrease farther in many locations across the North Island.
Hotspots in the North Island are currently found in Aupouri Peninsula, interior Manawatu-Whanganui, and interior Hawke’s Bay. In the South Island, only subtle soil moisture changes were observed in the past week.
However, hotspots remain in place across western Northland and Aupouri Peninsula, a small portion of central Waikato, southern Manawatu-Whanganui, and much of Wairarapa and southern Hawke’s Bay. In the South Island, soil moisture levels generally did not change significantly in the past week.
The driest soils across the North Island compared to normal for this time of year are found across the Far North and Kaipara Districts in Northland, western Auckland, around New Plymouth, in the Central Plateau, and along west coastal Manawatu-Whanganui.
In the North Island, another week of substantial rainfall is likely in many areas, which could lead to further soil moisture improvements. With substantial rainfall amounts anticipated in the next week, additional soil moisture improvements are likely in the northern half of the North Island.
Parts of Queenstown-Lakes District in Otago, the Grey and Buller Districts in the West Coast, northeastern Marlborough, and the Waimate District in southern Canterbury experience well below average rainfall for this time of year, while the rest of the island had near normal rainfall.