The temperature dipped below 45° setting a daily record in Boston on September 17, 2013. It hit 44° at Logan Airport around dawn on Tuesday, breaking the old record low temperature of 45° reached most recently in 1986. Weather records in Boston date back to 1872. Incidentally, the September 17, 1986 record low temperature had been the most recent September daily record low temperature set in Boston. Most of the record lows were set when the reporting station was not at Logan Airport which can be somewhat warmer due to its proximity to the ocean.
It was also in the low to mid 40s at the other major climatological sites in Southern New England, but no records were set for Worcester, Hartford and Providence. Hartford was the coolest of the bunch with a low of 40°. It was 41° in Worcester. Providence checked in at 44°. Many spots in the countryside dipped into the mid to upper 30s.