On the first Friday of every month, the U.S. government releases its Non-Farm Payrolls data from the month prior. The data is more commonly known as “the jobs report” and it swings a big stick on Wall Street.

Especially now — many analysts believe job growth is tightly linked to the future of the U.S. economy.

Therefore, when January’s jobs report hits the wires at 8:45 AM ET tomorrow, San Francisco home buyers would do well to pay attention. A net job reading that is much higher (or lower) than Wall Street’s expectations can make a serious change in home affordability.

Wall Street expects that the economy added 13,000 jobs last month.  It would mark the second time in 3 months that the jobs report showed a net monthly gain.

In November 2008, the economy added 4,000.

Jobs matter to the economy for a lot of reasons, but one of the biggest is that when Americans are working, Americans are buying and consumer spending accounts for 70 percent of the economy.

Job growth spurs the economy and draws money to the stock market. Unfortunately for rate shoppers, that kind of stock market growth happens at the expense of the bond market which is where mortgage rates are made.

Good jobs data usually means higher mortgage rates.

Also, job growth can lead to higher home prices. This is because working homeowners are less likely to default on a mortgage versus non-working homeowners.  In this way, job growth helps hold foreclosures to a minimum which, in turn, suppresses the housing supply.

Less supply means higher prices for home buyers.

Mortgage rates are idling this morning in advance of tomorrow’s data.  If you’re shopping for a mortgage rate, the prudent play may be to lock your rate before the jobs data is released.  A jobs figure that’s higher than the 13,000 expected could cause rate to rise sharply.

The Pending Home Sales Index rose slightly in December, climbing 1 percent from November.

A Pending Home Sale is a home that is under contract to sell, but not yet sold. It’s a figure compiled by the National Association of Realtors® using sales data from over 100 regional listing services and more than 60 large brokerages around the country.

Because each pending sale is a true measure of sales activity, the Pending Home Sales Index is purported to be the most reliable forward-looking indicator for housing. 

Recent data supports this hypothesis.

After Pending Home Sales plunged 16 percent in November, Existing Home Sales fell by 17 percent in December.  Based on the most recent Pending Sales Index, therefore, we can expect January’s closed sales to be similarly level.

For home buyers in San Francisco , this is all a bit of good news. Home prices are based on the supply-and-demand balance that exists between buyers and sellers.  When buyers outnumber sellers, like they did through most of 2009, home supplies dip and, in fact, the national home inventory nearly halved during the 12 months ending November 2009.

With fewer homes for sale, multiple-offer situations were almost commonplace and home values rose as result.

Activity has since slowed, however, and fewer buyers are in today’s market. The supply-and-demand equation has shifted back some. In December, home supplies rose for the first time in 7 months and January will likely show the same.

The net result: Home buyers have more homes from which to choose and that can create negotiation leverage for better prices and better concessions.

With mortgage rates still low and a looming deadline on the homebuyer’s tax credit, market activity should be strong between now and April.   Take your time and bid right. And when you’re ready, be ready. The best deals likely won’t last.