Dunedin's 60-year autumn sunshine record was broken by the 502 hours experienced from March to May, while Balclutha's 50-year record was also beaten with 495 hours, Niwa climate scientist Georgina Griffiths said.
Cromwell also recorded high sunshine hours - its tally was the third highest at 563.
The high sunshine hours reflected the sunny autumn experienced by most of the southern half of the South Island, she said.
No rainfall records were broken in the region.
"Most of the South Island rainfall was under three-quarters of normal.
"That is quite significant for a three-month period."
Otago figures followed that pattern - Musselburgh recorded 122mm (60% of normal), Queenstown 145mm (74%) and Ranfurly 71mm (61%).
Temperatures were cool, mainly due to the effect of easterlies during autumn, she said.
Throughout Otago, temperatures were similar and were average or near average, with Musselburgh recording an average of 11.4degC, Queenstown 9.6degC and Wanaka 10.6degC.
Niwa's May weather figures painted a similar picture for Otago to the overall autumn ones, Ms Griffiths said.
April's sunshine continued, with Queenstown experiencing record May sunshine hours since 1930 with 152 hours, although Dunedin was the cloudiest city in New Zealand with 120 hours.
Rainfall for May did not break any records but it was quite dry in places, with Oamaru recording only 10.6mm (27% of normal) and Dunedin 37mm (53% of normal).
Temperatures were about average for the month; the only significant figure was recorded at Ranfurly, which recorded the lowest temperature for May nationally with -8.1degC on the 20th.
Dunedin's mean temperature was 9.2degC while Balclutha recorded 7.7degC, Cromwell 6.8degC, Middlemarch 6.6degC and Oamaru 8.7degC.
