The number of existing home sales in the United States fell in August after three months of growth, according to the National Association of Realtors.

The organization says the seasonally adjusted annual sales rate dropped 4.8 percent, from 5.58 million in July to 5.31 million in August. Existing home sales are defined as completed transactions involving a condominium, co-op, single-family home, or townhouse.

The existing home sales rate was higher than the same month in the previous year for the 11th month in a row. August's sales were 6.2 percent higher than in August of 2014, when the annual sales rate stood at 5 million.

The median sale price for an existing home in August was $228,700. This price was a 4.7 percent increase from August of 2014, when existing homes sold for a median price of $218,400. The median price for existing homes has increased for 42 consecutive months.

Single-family homes accounted for the bulk of existing home sales, though these fell 5.3 percent in August to a seasonally adjusted annual rate of 4.69 million. This number dropped from 4.95 million in July, but was 6.1 percent higher than the pace of 4.42 million recorded in August of 2014. The median price for a single-family home also increased 5.1 percent from last year to $230,200.

The seasonally adjusted annual rate for condominium and co-op sales fell 1.6 percent, from 630,000 in July to 620,000 in August. This rate was a 6.9 percent year-over-year increase from August of 2014, when 580,000 of these units sold. The median price for a condominium of co-op in August increased 2.2 percent to $217,400.

Lawrence Yun, chief economist at the National Association of Realtors, says home price appreciation was more moderate in July and August than the increase in home prices earlier in the year. However, he says buyers may still be reluctant to buy due to a more limited number of available homes for sale.

Existing home inventory increased 1.3 percent at the end of August, standing at 2.29 million residences. However, the inventory is 1.7 percent less than in August of 2014, when 2.33 existing homes were available. The current sales pace puts the unsold inventory at a 5.2-month supply, an increase from the 4.9-month supply in July.

"With sales and overall demand higher than a year ago and supply mostly unchanged, low inventories will likely continue to limit options for those looking to buy this fall, even with the overall pool of buyers shrinking because of seasonal factors," said Yun.

Thirty-two percent of the people who purchased an existing home in the month were first-time buyers, a 4 percent increase from July and 3 percent increase from a year ago. This share also tied with May for the highest share of first-time buyers in the year.

Twenty-two percent of existing home sales in August were made entirely with cash, down 1 percent from the previous month and the previous year. Individual investors, 60 percent of home paid cash for a property, accounted for 12 percent of existing home sales in August; this share was the same as August of 2014 and 1 percent less than a year ago.

Seven percent of existing home sales were distressed properties, with foreclosures making up 5 percent and short sales accounting for 2 percent. This share was unchanged from July and 1 percent lower than in August of 2014. Foreclosures sold for 18 percent below market value on average, while short sales sold for an average discount of 12 percent.

Forty percent of existing homes sold in less than one month in August. Properties stayed on the market for a median of 47 days, up five days from July but six days below the median period in August of 2014. Short sales spent the longest time on the market at a median of 124 days, while foreclosures typically sold in 66 days.

The report notes that the average rate for a 30-year fixed rate conventional mortgage as reported by Freddie Mac was 3.91 percent in August. This rate fell from 4.05 percent in July, which was the first time rates hit 4 percent or higher since November of 2014.

"When the Federal Reserve decides to lift short–term rates—likely later this year—the impact on mortgage rates and overall housing demand will likely not be pronounced," said Yun. "With job growth holding steady, prospective buyers can handle any gradual rise in mortgage rates — especially if today's stronger labor market finally leads to a boost in wages and homebuilding accelerates to alleviate supply shortages and slow price growth in some markets."

Though no region experienced an increase in existing home sales, the Northeast was the only part of the United States where these sales did not decrease in August. The seasonally adjusted annual rate of 700,000 sales was the same as July and 2.4 percent above the August of 2014 rate. The median sales price for an existing home in the region was $271,600.

The Western region had the highest median home price at $321,300, a 7.1 percent year-over-year increase, but it also had the most noticeable decrease in existing home sales. The annual rate fell 7.8 percent to 1.19 million, which was still 7.2 percent higher than the previous year.

The South had the fastest annual rate at 2.14 million existing home sales, a 5.9 percent year-over-year increase but a 6.6 percent drop from July. The median price of an existing home in the region was $196,300, a 6 percent increase from August of 2014.

In the Midwest, the pace of existing home sales slowed by 1.5 percent to 1.28 million. This rate was still 5.8 percent higher than the previous year. The median price for an existing home increased 4 percent from the previous year to $181,100.