Hancock the weather man

Just behind Trinity Church is the original Hancock building, complete with it's weather forecaster on top. See the blue lit tower on top of the building? Here's how you use it to prepare for the ever-changing New England weather:

Steady blue: clear view
Flashing blue: clouds due
Steady red: rain ahead
Flashing red: snow instead (except during the summer, and then it means that the Sox game was canceled due to rain)