At sunset: 18 F (-7.8 C)
8 pm: 0.6 F (-17 C)
10 pm: -2.5 F (-19.2 C)
midnight: -5.6 F (-20.9)
3:30 am: -10.7 F (-23.7)
7 am: -12.8 (-24.9 C)
10 am: 9.1 F (-12.7 C)

Minimum: -12.9 F (-24.9 C)

I’m a bit west of Boston, but the previous Boston record low for this date is/was -3F/-19C (1967). I’m amazed at how fast the temperatures are falling tonight.