A patch of blue has opened up in the murky waters clouding the prospects for the housing industry. Both new home starts and new home sales rose in June, the latter well above expectations.

Builders received the news with guarded optimism, however, as a number of challenges still confront the industry. Among them, demand continues to outstrip availability as inventories shrink and prices rise.

Although Dodge registered a 2 percent decline in the value of residential projects in June from May, the latest figures from U.S. Department of Housing and Urban Development and the Commerce Department show a 4.8 percent increase in housing starts, based on number of units.

Single-family home starts rose 4.4 percent while multifamily starts bumped up 5.8 percent. Single-family starts are now up 13.2 percent for the first six months of the year, but slightly behind (2 percent) last June.

At the same time, the U.S. Census Bureau and HUD announced sales of new homes grew by 3.5 percent in June compared to May — 25.4 percent higher than a year ago and at their highest level since February 2008. In releasing the results of its Architectural Billings Index for the month of June, the American Institute of Architects noted "particularly strong growth" in business for firms with residential specialization.

All of this should be good news for builders. But lurking behind these rosy numbers are some unsettling trends.

Reuters reports new home sales are likely benefiting from a persistent shortage of previously owned houses available for sale. Trulia states sales of existing homes in June remained relatively flat (at 1.1 percent), largely due to a short of supply, echoing similar statements from the National Association of Realtors.

Pronouncing June’s housing market as the "fastest and most competitive on record," real estate brokerage Redfin said months of supply of existing homes is now hitting a low point at 2.8 months. Meanwhile, the supply of newly built homes is dwindling as well, down to a 4.9 months supply from 5.1 months in May.

New requests for building permits also stayed relatively flat in June (up just 1.5 percent over May) but are down 13.6 percent compared to a year ago. In addition, the median price of new homes sold in June reached $306,700, up from $288,800 in May, placing new homes further out of reach of many first-time buyers.

Added to these trends, other pressures, such as delays due to stricter regulations and shortages of labor and available lots, have dampened builders’ optimism.

The National Association of Home Builders’ builder confidence in the market for newly built, single-family homes in July fell one point to 59 from a June reading of 60 on its monthly Housing Market Index.

More telling perhaps, while perceptions of current sales and buyer traffic fell by just one point each, sales expectations for the next six months dropped three points, to 66, suggesting some mid-year readjustments to earlier forecasts have occurred. All of these numbers are still strongly in positive territory and could well improve in the months ahead.

Provided the economic news and employment figures remain positive, and availability of existing homes remains more or less the same, builders are hopeful, if cautious, business will pick up again heading into fall.

Housing data has been highly volatile on a month-to-month basis, and the market has seesawed between surges and lulls. One the whole, for the year the industry has been doing well. If supply continues to lag behind demand and inventories shrink further, however, it could experience some deceleration by the year’s end.