Lake Pukaki in the Mackenzie District plunged to an overnight low of -8C, according to MetService. Photo / File
South Islanders have woken to bitter cold this morning - with two towns measuring their lowest June temperatures in decades.
Middlemarch hit -12.3C overnight, the lowest temperature recorded this month in New Zealand since 2015, according to Niwa.
It's also the lowest June temperature for the Otago town since 2001.
Clyde hit -9.9C - the coldest June morning there since 1978.
Temperatures plunged overnight in the lower South Island because of a powerful high-pressure system over New Zealand.
Elsewhere in Otago, Ranfurly hit -9C, Alexandra dropped to -8.2C and Lauder got down to -7.9C.
The outskirts of Dunedin dropped to -7C around 6am while pre-dawn temperatures were at -8C around Twizel and Lake Pukaki.
Christchurch, Wanaka and Queenstown also hovered around -5C at 6am.
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Frosts and fog could linger around many areas in the South Island but once those burn off, the south can expect a fine day.
The North Island has much warmer temperatures - good news for this afternoon's sold-out match between the Blues and the Hurricanes at Auckland's Eden Park.
Current forecasts are for a few showers to clear the city early this morning, with cloud increasing during the day and northeasterly winds. A temperature of around 15C is expected for the 3.35pm kick-off.
Northland, Coromandel, Gisborne and Hawke's Bay can expect morning showers before fine spells in the afternoon.
The day will be mainly fine from Waikato through to Wellington, with some light rain possible around Taranaki from this evening.
Looking ahead, the current high will move east and offshore later today, with a milder subtropical northerly flow developing, forecaster Weatherwatch says.
By Monday night and into Tuesday, the milder winds will mean warmer-than-average overnight lows - meaning temperatures in parts of the South Island will move from several degrees below normal to several degrees warmer than normal within 48 hours.
Whangārei
Cloudy, one or two early morning showers. Fine spells for a time in the afternoon. Easterlies. High 16C, Low 9C.
Auckland
Cloud increasing. Remaining showers clearing early morning. Northeasterlies. High 16C, Low 9C.
Hamilton
Mostly cloudy. Light winds. High 14C, Low 3C.
Tauranga
A fine day with light winds. High 14C, Low 6C.
New Plymouth
Cloud increasing, occasional rain from afternoon. Northerlies developing in the evening. High 14C, Low 9C.
Napier
Fine with early frosts. Light winds. High 14C, Low 3C.
Whanganui
Fine, possible morning frosts. Cloud increasing evening. Southeasterlies dying out early morning. High 17C, Low 7C.
Wellington
Fine with morning frosts in sheltered places. Light winds, northerlies developing at night. High 13C, Low 7C.
Nelson
Fine. Becoming cloudy in the evening. Light winds. High 12C, Low 5C.
Christchurch
A fine day with morning frosts. Northeasterlies developing morning. High 11C, Low -1C.
Dunedin
Fine with morning frosts. Northeasterlies developing in the morning. High 11C, Low 6C.
The circumstances around the death are being treated as unexplained.