Hamilton housing prices set another record in May, rising 23.49 per cent from the same month a year earlier, according to the Teranet-National Bank house price index, which tracks price changes in the same properties over time.

Hamilton prices were up 3 per cent from April, matching a month-to-month increase record set in June 2014.

The gains in Hamilton prices helped raise the national index to its own record of 2.2 per cent, the largest month-to-month gain in the index's 19-year history.

It was the first full month of sales after the provincial government announced measures meant to cool hot housing markets in Toronto, Hamilton and the Greater Golden Horseshoe. The signals are mixed on what effect they are having. 

The May numbers in this price index didn't show much of an impact, said Marc Pinsonneault, a National Bank economist. 

But another measure of the local market released last week showed a spike in the number of houses listed for sale in May.

"So it's the same result that we had for Toronto, in that we haven't seen an impact on price but we've seemingly seen an impact on new listings and sales — the same applies to Hamilton," Pinsonneault said.

"My view, my feeling, is that we are still susceptible to see an impact on home prices, just that it didn't appear definitely (in May)," he said. "Expect something to be more and more obvious in the coming months."

The listings increase was announced last week by the Realtors-Association of Hamilton-Burlington, and showed 3,208 new listings were processed through the organization in May, which is 41.1 per cent higher than May of last year and 34.8 per cent higher than the 10-year average.

Toronto's prices increased by the most, proportionally, of 11 cities measured in the index – rising a record 3.6 per cent in May from April, and 28.7 per cent in May from a year earlier.

It's the 15th straight month that Hamilton prices have been rising.

Barrie, Oshawa, Peterborough, Kitchener-Waterloo, Guelph, Brantford and St. Catharines-Niagara also all showed "persistent uptrends" and double-digit increases from the year earlier, according to a release of the index.

Such dramatic increases across the Greater Golden Horseshoe "[justify] the Ontario government's application of its market-cooling measures to these markets as well as to Hamilton and Greater Toronto Area," Pinsonneault wrote.