Scorcher in store today

A sunbather watches a yacht sail toward Perfume Point, Ahuriri, Napier, yesterday. Photo / Warren Buckland

Hawke's Bay is expected to have its hottest day of the summer today, with a maximum 31deg forecast for Hastings.

A MetService forecaster says it comes with a norwester - "quite dry and warm" - but a front is due in the evening, with forecasts for a significant drop in temperature.

A maximum of just 19deg is forecast for Wednesday but Christmas Day will be more like an "average" Hawke's Bay summer day with a maximum of about 25deg on the Heretaunga Plains, about the same as yesterday's peaks.

The hottest temperature in Hawke's Bay so far this summer was on November 26 when a maximum of 31.4deg was recorded in Hastings, while the hottest official temperature reported in Hawke's Bay last summer was 33.3deg in Wairoa on January 5.

It's expected to be even hotter today in the Big Hill Station woolshed west of Hastings, where Hawke's Bay shearers Errol Chrystal, nephew Kalin and workmate Shelford Wilcox will be tackling a world record, starting at 7am and finishing at 5pm.

The shearers will be out to shear a total of at least 1500 sheep, similar to the number of calories they can expect to lose between them during the day.

Record-breaking temperatures swept through the South Island yesterday, with a peak of 36.1deg in Christchurch, beating the city's previous December record of 35.4deg measured in 1975.

Dunedin hit 30deg before 11am and, according to Metservice, was at 31.7deg at 6pm, while Ashburton touched just below 36deg early in the afternoon, short of its hottest December temperature of 36.3deg in 1971.