* The median forecast is for the S&P composite index of 20 metropolitan areas to be unchanged in December from November, non-seasonally adjusted, and down 3.2 percent from December 2008. This would follow a 0.2 percent November monthly decline and 5.3 percent annual drop.
* The median forecast is for a rise of about 5.3 percent in January new home sales to 360,000 annual units, following a 7.6 percent drop to 342,000 units in December.
* The median forecast is for a 1 percent rise in January existing home sales to 5.50 million units, after a 16.7 percent plunge in December.
FACTORS TO WATCH
U.S. home prices probably stagnated in December, with the S&P/Case-Shiller 20-city index showing no change after a 0.2 percent November decline and a total average price plunge of about 30 percent from 2006 peaks.
The rate of annual decline also continued to improve, based on the median forecast in a Reuters poll, with a 3.2 percent drop expected to follow the 5.3 percent downturn in November.
Economists in a separate Reuters housing poll last week said the bottom had probably been reached but prices were unlikely to gain this year. The 20-city index would be unchanged in 2010 before rising 2 percent next year, the poll found.
But even stability is welcome after prices tumbled for more than three years, helping send the U.S. housing market into freefall and the economy into recession.
Housing is gaining some traction on the back of massive government aid, including buyer tax incentives that are set to end this spring.
After harsh December weather kept many buyers inactive, sales of both new and existing homes rose modestly in January, economists said. Home shoppers aimed to take advantage of near record-low mortgage rates and the tax credits before they disappear.
Qualified borrowers need to sign contracts by April 30 and close loans by June 30 to get the $8,000 first-time buyer credit or $6,500 move-up credit.
Sales of new homes rose about 5.3 percent to 360,000 annual units after slumping 7.6 percent in December, and sales of existing homes climbed 1 percent to 5.50 million units after a 16.7 percent December plunge, based on Reuters surveys.
No. 2 U.S. home improvement chain Lowe's Companies
Home Depot, the largest home improvement chain, is set to report its quarterly results on Tuesday and is seen outperforming Lowe's. Sales had been lackluster at both companies with customers delaying major home renovations during the housing and economic downturns.
Also, new homebuilding rose to a six-month high in January, surpassing forecasts and pointing to stabilization.
Thirty-year mortgage rates averaged 5.03 percent in January, virtually the same as the average for all of 2009, according to home funding company Freddie Mac. The rate got as low as 4.71 percent in December, the lowest since Freddie Mac started tracking rates weekly in 1971.
Home loan rates are seen rising through the year, however, as another key government intervention ends. The Federal Reserve by March 31 will have completed purchases of more than $1.4 trillion in mortgage-related securities aimed at lowering borrowing costs to revive housing and the economy.
Rising borrowing costs, and the looming flood of repossessed properties that banks have yet to put up for sale, should prevent much of a near-term housing recovery, most economists agree.
(Reporting by Lynn Adler; polling by Bangalore Polling Unit; Editing by Andrew Hay)