Calgary home sales plunged in August compared with last year as weakness in the energy sector continued to weigh on the housing market.

Home sales dropped almost 27 per cent in the month compared with a year ago to 1,643 units sold, a figure that was about 12 per cent below the 10-year average, according to the Calgary Real Estate Board.

"Persistent weakness in the energy sector weighed on sales activity this month, which once again retracted to levels well below the norm for the city," CREB chief economist Ann-Marie Lurie said in a statement.

Over the summer, sales were down significantly compared with last year's strong figures, but they were only a few percentage points below the long-term average.

The city saw a similar drop in April, when home sales were 22 per cent lower than last year and nearly 15 per cent below the long-term average.

Inventories of homes climbed in August to 3.1 months of supply, compared with 2.5 months at the end of July.

Houses selling for more than $600,000 made up a higher proportion of listings compared with last year, but the higher-end homes saw a drop in the share of total sales.

"With more options in the higher-end of the market, sellers will need to consider their competition as well as their goals regarding a sell date," said Lurie.

With fewer sales in higher-end homes, the average sale price dropped 1.94 per cent to $466,462 in August, while the benchmark price was down less than 0.1 per cent from a year ago at $456,300.

The condo sector has been harder hit as increasing competition has pushed inventories up to 4.3 months of supply. That has put pressure on prices, with the benchmark price down 1.4 per cent compared with last year at $294,100.