Houston-area home sales continued their upward trend in September, registering an 8.7 percent gain over September of last year, the Houston Association of Realtors reported.

For 16 months in a row, home sales in Houston have been in positive territory, demonstrating that the city is one of the strongest housing markets in the nation.

Through the first nine months of the year, Houston home sales totaled 46,967, up 14 percent from the 41,050 sold in the comparable nine-month period of 2011, the Realtors association said.

This year is shaping up to be one of the biggest ever for Houston home sales.

The inventory of homes for sale has been dwindling significantly. The Realtors association reported 39,319 listings were available at the end of September, a 17.8 percent decline from a year ago.

The inventory of single-family homes for sale is now a 4.7-months supply. For years, the accepted industry wisdom has been when inventory falls below a six-month supply, it becomes a seller’s market, meaning the seller has the upper hand over the buyer.

“The lack of inventory is pushing up home prices,” said Shad Bogany of Better Homes and Gardens Real Estate (Gary Greene).

Sales City

The upper-end of the market is exceptionally strong, Bogany said, but deals for houses of less than $100,000 are getting rare because there just aren’t many affordable homes for sale anymore.

Even though sales are good in most areas, there are still pockets of softness. And if a seller gets too greedy, buyers may bypass them.

“Sales are up, but if they aren’t priced right, the homes won’t sell,” said Realtor John Buchanan of Re/Max Cityview.

Uncertainty about the national economy and the presidential election, may be making some other would-be buyers skittish about moving ahead, Buchanan said.

But with mortgage rates available at below four percent and Houston one of the leaders in job growth, the local housing market has been excellent. Home sales in August were the best in five years. The summer — traditionally known as the best season for home sales — was impressive enough to keep Realtors smiling through the always-sluggish winter months ahead.

“Demand for homes throughout Houston continues to outpace supply as we transition into the fall season,” said Wayne Stroman, HAR chairman and CEO of Stroman Realty. “Home sales traditionally begin to taper off this time of year, so we are not worried about inventory declining to unhealthy levels.”

The single-family home average price increased 4.7 percent year-over-year to $220,992, the highest level for a September in Houston. The median price — the figure at which half of the homes sold for more and half sold for less — climbed 6.1 percent to $165,000, also a record high for a September in Houston.

Looking forward, the Realtors association reported that the pending sales activity was up in September, compared to September of 2011, so the market will continue to be reasonably good this fall, even though it will taper off from the strength of the torrid summer.