A variety of data released this week show the housing market is improving, although more than a third of Charlotte-area homeowners still owe more than their homes are worth.

Nationally, people bought more new homes in July than the previous month, the government reported Thursday. Sales of new single-family homes rose 3.6 percent to a seasonally adjusted annual level of 372,000 units and matching a two-year high, according to the Census Bureau. The last month more new homes were sold was April 2010.

The National Association of Realtors this week reported improving sales of existing homes for July, saying sales of existing single-family homes, townhomes, condominiums and co-ops grew 2.3 percent to a seasonally adjusted annual rate of 4.47 million in July, up from 4.37 million in June and 4.05 million a year ago.

Existing-home sales in the South rose 2.3 percent from June to an annual level of 1.77 million, up 8.6 percent from July 2011.

Such sales rose highest in the Northeast, which saw a 7.4 percent increase over the previous month. Existing-home sales increased 2 percent in the Midwest and stayed flat in the West due to inventory shortages, the association said.

Foreclosure rates for the Charlotte area, however, rose in June compared with the previous year, research firm CoreLogic reported, reflecting how a weakened economy continues to weigh on homeowners.

The foreclosure rate for the Charlotte-Gastonia-Rock Hill area hit 3.21 percent in June, up from 3.02 percent a year ago. Local foreclosure activity is lower than the national foreclosure rate, which was 3.27 percent in June.

What may be a sign of improved conditions to come: The local mortgage delinquency rate fell for the fifth consecutive month to 6.72 percent. The rate shows the percentage of homeowners that are 90 days or more behind on loan payments. A rising delinquency rate typically means more foreclosures are to come, which would further depress the market.

Still, the housing market remains challenging even for those who can afford to pay their mortgage. Thursday, real estate research firm Zillow released data showing the Charlotte metro area is underwater by $6.9 billion. About 130,000 area homes are thought to be underwater. This affects 36.4 percent of Charlotte-area homeowners.

Nationally, 31 percent of U.S. homeowners are estimated by Zillow to be underwater.

Most underwater Charlotte homeowners are still paying their mortgage on time, according to Zillow. About 9 percent are more than 90 days delinquent, compared to a national delinquency rate of 9.2 percent.