Severe winter weather across much of the U.S. has held back growth in the economy so far this year, a closely watched report out of the Federal Reserve said Wednesday.

The so-called Beige Book summarizes economic activity from 12 regions across the U.S. that the agency monitors. Eight of the 12 regions showed improvement described as "modest to moderate" due to improvements in things like the job market and real estate.

But the weather was a factor across the country — and in some places a major one.

New York and Philadelphia, two regions hard hit by winter storms and freezing cold, reported a big dip in economic activity attributed to the weather.

In both areas, retail sales and car purchases were lower than they would have been otherwise. Manufacturing was also lower as factories reported power outages and slower delivery times all along their supply chains.

The summary and the individual reports from each of the 12 regions were sprinkled with numerous references to the harsh weather much of the country has endured this winter.

The statement used the word "weather" 119 times — a sign of how prevalent it has been lately, as an economic factor.

The report said retail sales had weakened in many districts because of the winter storms. Nine districts — Boston, New York, Philadelphia, Cleveland, Richmond, Atlanta, Chicago, St. Louis and Dallas — reported that the severe weather had hurt factory production and manufacturing sales.

The report said the weather had caused power outages, disrupted supply chains and curtailed factory production schedules.

"Much of the slowdown in activity indicated by recent data is attributable to adverse weather conditions," Royal Bank economist Josh Nye said in a research note after the Fed report came out. "Aside from this factor, most districts continue to see a modest to moderate pace of growth."

The Beige Book is based on anecdotal reports from businesses themselves. It's a big part of the data the Fed looks at in making its interest rate decisions.

When the Fed meets to consider that decision next week, it will be the first policy set since Janet Yellen took over the top job from Ben Bernanke. As such, it will be even more closely watched than usual, with a special focus on signs of her intention toward tapering off the agency's aggressive bond-buying program.