The number of rental apartments that sat vacant in April climbed to 3.2 per cent in Calgary and 2.4 per cent in Edmonton. Both cities had rental vacancy rates of 1.4 per cent a year earlier.
Regina's rental vacancy rate climbed to 4.8 per cent in April, from 2.5 per cent a year ago.
Meanwhile, the rental market tightened in Vancouver to 1.4 per cent, from 1.8 per cent previously.
Toronto's vacancy rate remained relatively flat, at 1.8 per cent, from 1.9 per cent previously.
Renters in Vancouver paid the highest average rent for a two-bedroom apartment, at $1,345 per month. Calgary came in second at $1,319, followed by Toronto at $1,269.
CMHC chief economist Bob Dugan said stronger economic conditions in Ontario and B.C. offset the negative impact of energy prices in Western Canada, leaving the national average vacancy rate relatively flat in April at 2.9 per cent.
That compares to 2.7 per cent in April 2014 — a change that the CMHC says is not statistically significant.
"In Ontario, improving employment conditions for young adults aged 15 to 24, a key source of rental demand, and a stable supply of rental units placed downward pressure on vacancy rates, while increased immigration to British Columbia, another key source of rental demand, more-than-offset an increase in the province's rental market supply," Dugan said in a news release.
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