Cooler weather arrived on the heels of a strong cold front swinging down from Canada. The cold front passed by the South Portland weather sensors of Weather Maine at around 5:30 PM on October 2, 2003; the time period (10 mins) of the lowest barometric pressure was at 5:20PM on this date, 29.87" Hg.

Barometric pressure typically rises after frontal passage. Winds quickly turned to the NW and became gusty. During the next half-hour after frontal passage, there was a very brief period of moderate rain with, interestingly, some embedded thunder.
This cold front spells trouble for many agricultural interests around Maine.

The National Weather Service in Gray, Maine issued a freeze warning for the inland areas of Maine. A freeze warning is issued when below-freezing temperatures during the growing season are expected. Frost is expected to affect most of Maine, outside of the coastal fringe areas.
Addenda: No frost was seen during this cold snap at the South Portland, Maine location.