Sales spiked an average of 19.5 percent for distributor members of the Heating, Air-Conditioning and Refrigeration Distributors International during December, the association said.

Five of the association’s seven regions showed sales growth above 20 percent for the month.

“The month-to-month performance can be volatile,” said HARDI market research and benchmarking analyst Brian Loftus, who compiled the statistics with association senior economist Andrew Duguay. “The strong growth report for December reflects a couple factors. This year had one extra billing day than the prior year; we had an extremely cold period that stretched across much of the country this season, and the December 2012 sales were quite weak across the majority of the country.”

Many HARDI members said had a good year, Duguay added.

“A full 80 percent of members reported higher sales in 2013 versus the year prior,” he said.