"Indian Summer" technically applies to a stretch like this that follows a hard freeze, defined as temperatures in the upper 20s.
Some parts of the region would qualify under those criteria, although the thermometer hasn't yet approached freezing at Philadelphia International Airport.
In the court of common sense, however, we'll declare this Indian Summer.
Temperatures are going to race into the 70s every day this week, and could make runs at the Philadelphia records on Thursday and Friday.
The Thursday record, 76, was set in 1993, 2001, and 2010. The forecast high is 74, and that's likely to be tweaked some during the next few days.
The Friday stand, 78, set in 1920, will be tougher to reach, but the forecast high of 75 isn't exactly a cold wave.
Ultra-warm spells in October aren't unusual. In 1920, for example, the highs on the 25th and 27th were 74 and 75, respectively.
In 2001, it reached the 70s for six straight days from the 20th to the 25th.
The magnificent run of weather will end, of course, and already a nascent tropical storm is gaining some buzz.
That thing is due to become "Sandy" tomorrow, and it could affect our weather late in the weekend.