Stephen Colbert:
(Washington D.C., 13 May 1964).
American actor, comedian, producer and author.
He is best known for his years as a correspondent on Jon Stewart’s television programme The Daily Show and as host of his own programme, The Colbert Report. Since 2015, he has presented the talk show The Late Show with Stephen Colbert on CBS. He is also known for promoting the English-language word truthiness as a description for one’s own view, uninfluenced by reason or contradictory evidence, with which Colbert parodied George W. Bush, neoconservatives and religious fundamentalists.

It’s Fourth of July weekend, or as I call it, ‘Exploding Christmas’.

It’s a joke about the fact that the 4th of July, like Christmas, is a big, festive American family celebration — with gatherings, food, and gifts/traditions — but with the quintessential American element of fireworks (“exploding”) instead of the quiet, snowy atmosphere of Christmas. The humor lies in the contrast between the cozy image of Christmas and the noisy, explosive nature of July 4 celebrations (barbecues, fireworks, patriotism).
Origin:
The quote is dated July 4, 2015, and has been circulating around this time every year in lists of funny 4th of July quotes. I haven’t been able to find an exact context (which show, which episode).
Author: It seems best known as a loose, oft-quoted one-liner by Stephen Colbert, probably from his late-night show or standup, but the source articles only mention the year 2015 without mentioning a specific program.