However, the rental market in Wellington tended to be seasonal and Jeffries expected it to ease back as autumn approached.
"It remains to be seen whether we'll see median weekly rents in the capital break $500 but we'll be watching with interest," he said.
Median weekly rents continued to edge up across the rest of New Zealand last month, with Auckland prices going up another 4 per cent to $520 per week.
Hawke's Bay and Waikato saw the biggest year-on-year leaps in median weekly rent, up 12.5 per cent and 11.4 per cent respectively.
Canterbury and Gisborne had declines in median weekly rent for the fifth consecutive month while the West Coast had its second consecutive monthly dip.
Townhouses in Wellington and Auckland saw new peaks with Auckland up 7.2 per cent to $595 a week and Wellington up 14.6 per cent to $550 a week.
The average rental property in New Zealand was last month worth $450 per week.