"I just question whether the retailers will give enough discounts to get shoppers into the stores," he said. Although Black Friday, or the day after Thanksgiving, generated a 4.8% increase in traffic, industry watchers say things have tapered off considerably since. The first two weeks of December saw a lull, and only now are the crowds starting to come back. In San Francisco's Union Square shopping district over the weekend, customers carried armloads of red shopping bags from Macy's. Crosswalks were jammed with slow-moving clusters of people trying to make it to the other side before the light turned red. In other parts of the country, however, wintry weather kept some shoppers away. Ellen Davis, a spokeswoman for the National Retail Federation, which predicts holiday sales will be up a slower-than-average 4%, says heavy snowfalls made it tough on retailers. But it's hard to gauge how much of an impact the weather ultimately has on consumers. For instance, last year during the holidays, retailers said warm temperatures discouraged shoppers from purchasing thick sweaters and coats. This year, cold temperatures could make people want to huddle in their homes. Christine Chen, an analyst from Needham & Co., says cold weather is only a problem if it keeps shoppers away for prolonged periods of time. One day of heavy snow is not enough to ruin holiday sales for a retailer, although it certainly hurts if it happens during the peak of the season.