Bite your tongue, Nyboy! We can have a long period of beautiful fall weather before the frost arrives and I want every degree day I can get. Mums like the fall just fine.
A bit of both, Nyboy. Indian summer is the period after the first killing frost, that falls between specified dates or it is any unexpectedly warm weather period between late October and mid November that follows a hard frost depending upon the lore in your area.
Around here in South-est, Central-est Wisconsin, it is an abnormally warm and dry weather period, varying in length, that comes in the autumn time of the year, usually in October or November, and only after the first killing frost or freeze. There may be several occurrences of Indian summer in a fall season or none at all.
For you, being a New Yorker, the Farmers' Almanic defines Indian Summer:
As well as being warm, the atmosphere during Indian summer is hazy or smoky, there is no wind, the barometer is standing high, and the nights are clear and chilly.
A moving, cool, shallow polar air mass is converting into a deep, warm, stagnant anticyclone (high pressure) system, which has the effect of causing the haze and large swing in temperature between day and night.
The time of occurrence is important: The warm days must follow a spell of cold weather or a good hard frost.
The conditions described above must occur between St. Martin's Day (November 11) and November 20.
I still see no reason to look forward with anticipation to the first killing frost. There are years with no warmth following that freeze. Last year in Wisconsin, for example, we had a killing frost in September with October reaching temperatures well below freezing and frost fingering its way into the ground. November could have been considered warm next to October, with its normally cool temperatures, but nothing like we associate with Indian Summer.
Your mums will be happy with the gradual decline in average temperatures that comes with September. From an average daytime temperature of 81 in August, we fall to an average of 62 in October. Certainly more comfortable as winter approaches. No need to wish our beautiful autumn period away in hopes of an iffy, fleeting chance at a week of Indian Summer sometime in the future.