Builders’ recent anecdotes about better buyer traffic and sales turned out to be right on the money. According to Monday’s report from the U.S. Census Bureau, sales of new homes jumped 11% in June on a monthly basis to a seasonally adjusted pace of 384,000 homes, surpassing analysts’ expectations. Compared to the same month a year ago, that represents a 21.3% decline in sales activity.

(Wall Street watchers had projected a seasonally adjusted level of 352,000 sales for June.)

But builders shouldn’t break out the champagne just yet. “The new home sales estimates are extremely ‘noisy,’” with lots of volatility, cautioned Patrick Newport, U.S. economist for IHS Global Insight, who advised builders to look at sales over recent months, not just the current month.

Still, even with a more conservative perspective, sales do seem to be improving over time. “A three-month moving average shows that new home sales appeared to have hit a bottom in January and are starting to grow ever so slightly,” Newport said. “By region, sales have started to pick up in the West and Midwest, and are leveling off in the South and Northeast.”

A major factor in the June figures is certainly the $8,000 federal tax credit for first-time home buyers, which builders say has resulted in traffic and sales. As a result, their inventory continues to drop; in June, builders had 281,000 homes for sale, which would be considered low in a normal market. In this downturn, though, that represents 8.8 months worth of supply.

Sales prices also showed softness in June. The median sales price dropped 5.8% last month, to $206,200 for new homes. In comparison, the median sales price for existing homes in June was $181,800, according to the National Association of Realtors.

“Although the market for new homes is improving, selling a new home has never been harder,” Newport said. “The median time that a new home sits on the market before selling rose to an all-time high of 11.8 months. The number is rising because builders must cover their costs and do not have the option of selling homes at ‘fire sale’ prices.”

Builders are also encountering problems with the new appraisal rules.

Alison Rice is senior editor, online, at BUILDER magazine.