45°South Weather Services owner Andy Fraser with a thermometer and sunshine recorder at the Invercargill weather station, on Friday morning.

Invercargill is set to mark a rarity on Sunday, with the temperature expected to soar to 30 degrees Celsius.

45°South Weather Services owner Andy Fraser said it was not often that the temperature hit 30C in Southland.

The high temperature is expected to stick around on Monday, which is also predicted to hit 30C in Invercargill and Gore.

Invercargill's hottest day was 32.2C, recorded in January 1921. Gore's highest temperature was 32.9C in February 1999.

According to MetService, there have been only 18 months that recorded a temperature higher than 30C since 1905 in Invercargill.

Invercargill has just come out of the equal-driest year since records began in 1901.

Weather records began in various locations in Invercargill in 1901, and at the airport since 1939, and the only other time it had been this dry was in 1947, Fraser said.

The thing that had caused the driest year was the persistence of anticyclones over New Zealand for so many months, which was unusual, he said.

Invercargill had received only 4.3mm of rain in the 12 days of January, Fraser said.

Invercargill at this time of year usually would have between 40 to 45mm of rain during the first 12 days, he said.

"We've only had 10 per cent of normal annual rainfall."

Computer models were suggesting Invercargill was going to have periods of showers starting to spread over the region from about Tuesday, Fraser said.

MetService meteorologist Tom Adams said Southland was looking better off in terms of weather for what the country was set to get in the coming days.

"The daily maximum temperature average is 18.5 degrees [in Invercargill], so this is significantly above average," Adams said

While temperatures were likely to stay above average for the rest of the month, the 30C highs were not going to become the new norm, he said.

There might be one or two days where there were similar high temperatures in the rest of the month, he said.

The high temperatures are set to drop off on Monday night and periods of rain for the south are expected throughout the rest of the week.

A sun protection alert from Niwa advises that people should slip, slop, slap and wrap between 9.35am and 6.05pm on Sunday to protect their skin and eyes from the sun's damaging rays.

Fire and Emergency New Zealand principal rural fire officer Elton Smith said the hot weather forecast for this weekend and early next week meant a fire could easily break out.

Fire and Emergency NZ was asking people to extinguish any existing fires and not to light any more over the next four days, including charcoal barbecues, braziers, camp fires, and incinerators, Smith said.