It was forecast to reach 19degC at Dunedin airport tomorrow.
The National Institute of Water and Atmospheric Research's record daily maximum temperature for Dunedin on June 22 was 17.4degC, in 1998.
The record daily maximum for the month of June is 20.6degC on June 9 last year and June 7, 1989.
The forecast temperature comes after the shortest day today when southern towns and cities would receive only about eight and a-half hours of daylight, compared with about nine and a-half in the north.
Niwa meteorologist Ben Noll said the winter solstice occurred at 10.34am today when the sun's position in the sky was at its farthest point north of the equator.
It meant today had the least amount of daylight of any day this year, he said.
After tomorrow, daylight hours would begin to increase.
There would be two to three more minutes of daylight by the end of the month and almost an hour by the end of next month.
The MetService was also predicting 19degC tomorrow and had recorded a top temperature in June of 20.4degC in 2003.
MetService meteorologist Lisa Murray said high temperatures had already been experienced this month, 18degC being recorded on June 9.
Winds would turn northwest tomorrow, accounting for the temperature rise, she said.
"It's relatively warm air compared with the southerlies we've had.
"It's pretty warm for this time of the year.''
Eastern Otago towns would all reach the high teens tomorrow while inland Otago towns would hit about 15degC, she said.
Shortest day, June 21
| Place | Daylight |
| Invercargill | 8hr 35min 5sec |
| Dunedin | 8hr 39min 17sec |
| Christchurch | 8hr 56min 27sec |
| Wellington | 9hr 11min 28sec |
| Hamilton | 9hr 32min 41sec |
| Auckland | 9hr 37min 58sec |
| Whangarei | 9hr 44min 7sec |
