The Far North rent rise was $20 to $370 over the same period.
Ruakākā mum-of-four Rochelle Powell is moving her family of six into a one-bedroom unit after her landlord decided to sell the house.
The Powells have lived in the four-bedroom house, owned by a family member, for seven years and are struggling to find a similar size property at an affordable price.
"The only way it's going to work is for my youngest child to go to a childcare and for me to find part-time work. We can only afford to spend $350 a week on rent," she said.
Her family has until September 9 to move out. Since her husband works at the New Zealand Refinery, they prefer to live in Ruakākā long-term.
Head of Trade Me Property Nigel Jeffries said demand in Northland was right across the board for all types of rental properties from one-bedroom units to five-bedroom houses.
"There's no particular spike in demand or prices at this time of the year. The expectation is that rents in Northland will continue to grow above the inflation rate.
New Zealand's current inflation rate is 1.1 per cent.
Jeffries said Northland's rental prices would likely level off in the next 12 months and come down by between 2.5 per cent to 4 per cent.
"We don't normally see regions running very high rates for a long time. We're saying rents will continue to grow in Northland but the rate would not be sustainable as people cannot dip into their pay packets."
He said an increase in median rate of 5.3 per cent over 12 months in Northland was not unexpected because of the very strong growth in Auckland in the last couple of years.
People staying longer in rental properties further exacerbated the demand for such units and houses, he said.
The median rent in Northland in January was $385, dropping slightly to $380 in February before rising to $400 in April.
There are 235 residential property listings on Trade Me.
While the national median weekly rent was up 5.6 per cent on last year, it stalled in May and remained at April's record-breaking $475 per week.
Rental properties in the Hawke's Bay are still a hot favourite and the most popular on Trade Me in May was a 5-bedroom house which had an astounding 92 enquiries in the first two days onsite.
Auckland's rental market has eased off a bit with supply picking up and better meeting demand.