A Niwa spokesman said as of February 14, the New Zealand Drought Index showed "dry to extremely dry" conditions were now located in large portions of the northwestern and lower South Island.
"In the South Island, significant rainfall associated with Cyclone Gabrielle affected far northern Canterbury, where amounts of more than 100mm were observed.
"Between 75mm and 100mm also occurred in Banks Peninsula, with 25mm-50mm in central Canterbury.
"However, the remainder of the South Island saw little, if any, rainfall in the past week."
He said this resulted in moderate soil moisture increases in northern Canterbury and Banks Peninsula, but notable decreases were observed across the remainder of the South Island.
"The driest soils in the South Island, when compared to normal for this time of the year, are located in northern Buller district.
"South Island hot spots are currently located in nearly all of southern Canterbury, Otago, and eastern and interior Southland.
"In addition, a small portion of southeastern Otago has entered meteorological drought."
He said on Tuesday and Wednesday next week, a plume of moisture was expected to affect the lower South Island and West Coast, and could result in moderate to heavy rain occurring on the West Coast, Otago, and Southland.
"Weekly rainfall totals could reach or exceed 100mm in the central and lower West Coast, with 25mm-50mm possible in the lower South Island.
"However, lighter amounts of 25mm or less are likely across the remainder of the island."
He said the expected rainfall could increase soil moisture levels in much of the West Coast, along with at least small improvements in the lower South Island.
But much of the upper and eastern South Island was likely to see continued small soil moisture decreases.
Voluntary water restrictions remain in place for Dunedin, and yesterday the Queenstown Lakes District Council announced water alert level 1 restrictions for Arthurs Point, Luggate and Lake Hāwea are now in effect.
The QLDC restrictions require residents to keep hand-held hosing to a minimum at all times, and only use irrigation systems between midnight and 6am.
A total fire ban and prohibition on fireworks is also now in place for most of Otago, meaning all previously granted fire permits are suspended, and most of Southland is a restricted fire area.
Dunedin City Council parks and recreation group manager Scott MacLean said Dunedin was very dry at the moment and asked people to be extra cautious in forested areas such as Signal Hill, Frasers Gully, Ross Creek, Bethunes Gully and the Silver Stream water race tracks.
"We’re following Fire and Emergency New Zealand advice that our reserves are extremely dry, and gusty winds mean any fire that starts will spread quickly.
"It takes only one spark to cause a wildfire, so please do your bit this summer."
