Dunedin was the coolest and cloudiest of New Zealand's six main centres last month.
Its average temperature was 10.2degC, 0.7degC lower than normal and 0.7degC lower than Christchurch (10.9degC) and 4degC less than Auckland, Niwa's October climate report shows.
It was also well short on sunshine with only 152 hours recorded compared with Christchurch's 212 and Tauranga's 236.
Climate scientist Georgina Griffiths said it was a relatively stormy October with more frequent southwest winds and lower pressures than normal affecting New Zealand.
The winds made for cool month for the south and west of the South Island with temperatures between 0.5degC and 1.2degC below average, she said. The national average was 11.8degC.
Around the region, Balclutha recorded its fourth lowest mean temperature of 9.1degC, -1.4degC below normal, while Ranfurly recorded its third-highest daily maximum of 23.6degC on October 30. Near-record low daily temperatures were experienced in Wanaka, 5.8degC on the 13th; Cromwell, 6.8degC also on the 13th; and Balclutha 7.8degC, on the 6th - all were the towns' fourth-lowest recordings.