WARNER ROBINS -- As cold rain soaked the area Monday, Mattie Brown scurried toward the post office, balancing three packages.

She wrapped her arms around the boxes, keeping them in place with her chin, and breathed a sigh of relief when she entered the lobby. She still had a few more trips to make.

“It’s quite a hassle. I’ve got 10 boxes,” said Brown, of Warner Robins. “And this weather doesn’t help.”

Dreary weather did not keep Brown and other customers like her away from Middle Georgia post offices on the nation’s busiest mailing day of the year.

The U.S. Postal Service anticipated Monday to be the biggest mailing day for holiday cards and packages, with more than 655 million pieces of mail expected to be processed compared to 538 million on an average day. The USPS predicts a record-setting holiday season, with 365 million packages expected to be delivered -- that’s a 20 percent increase compared to 2011. The U.S. Postal Service attributes that increase to the rising popularity of online shopping.

By 1 p.m., holiday traffic had been slower than usual at the Warner Robins post office, postal officials said, but a short line still stretched from the service counter, and a constant stream of customers carried boxes in and out of the office on Russell Parkway.

While Monday’s weather kept crowds down, on Saturday “we were slammed,” said Karen Bridger, business service network representative with the North Florida postal district. “Warner Robins is one of our busiest offices.”

Bridger was sent from Jacksonville, Fla., to work as a lobby director in Warner Robins, where she instructed customers, helped prepare packages and communicated with workers who sorted piles of letters and packages. Workers were trained to keep lines as short as possible, Bridger said.

In Macon, a lobby director was on hand at the Peake Road location. Rainy conditions did not affect customer traffic at that office, where long lines were constant Monday, said Cynthia Tuft, customer service supervisor.

“It’s been all day,” she said about the crowd.

Employees began preparing for this day a few weeks ago, and extra workers were on hand Monday to help sort mail, Tuft said.

“We don’t let a truck come in and leave empty,” she said. “We send everything out as soon as we can. As soon as we can get the containers filled, they’re out the doors.”

In Byron, Postmaster Mary Willis was overwhelmed with mail Monday as she and one other workers handled boxes, packaging, stamps and envelopes. A line of customers stretched from the service counter all day, she said.

“It’s been out the door the entire day,” she said, adding that the weather didn’t keep the crowds away. “I would have thought that it would, but it hasn’t.”

Back in Warner Robins, customers balanced umbrellas and fragile boxes. They pulled their raincoats tight as they gripped packages, bags and envelopes. Four workers stood behind the service counter, ushering people through as quickly as possible.

Quilla Mehrhoff had one package to mail this year, and she picked the busiest mailing day of the year to do it. But the Warner Robins woman was surprised at how quickly the line moved.

“Today was the fastest I’ve been in and out,” she said.

As she tugged a hat on her head in preparation for the third trip to her vehicle, Brown said she was pleasantly surprised by the small crowd.

“I am really shocked. Usually (going to) the post office is unnerving. ... It gets pretty darn crowded,” she said.

But it’s a holiday routine for Brown, who mails multiple packages to her grandchildren. As the rain began to slack, Brown slid her last three packages on the lobby counter.

“These are my last,” she said.

To contact writer Jenna Mink, call 256-9751.