At midnight on Christmas Eve and New Year's Eve, the whole town rings out with mortars and roman candles and little trees (all literal translations of the names of the firecrackers).
It's a tradition made possible by both warm weather as well as the attitude toward community. It's totally normal to step outside an shoot off incendiaries right next to your neighbor.
And if they happen to land on his roof, well, let's hope he doesn't notice (thank goodness for zinc roofing and concrete block walls)!
For my part, I tried to spell out Feliz Año Nuevo and Happy New Year's with sparklers for you.