During baseball season, flashing red means the Boston Red Sox game has been called off on account of weather.
In October of 2004, the beacon flashed red and blue to commemorate the Boston Red Sox World Series victory. This was the first time the color scheme changed since the beacon was lit in 1950. A new line was added to the poem accordingly:
Flashing Blue and Red, when The Curse of the Bambino is dead!
The beacon again flashed red and blue when the Red Sox won the 2007 World Series.