Actually, since yesterday, we are having rain and cool temperatures, which are expected to last for about a week or so. But we had at least three heat waves since last June.
Quite a few fruit, crop and/or vegetable harvests started much earlier than usually, like the grape harvest, which is about 3 weeks ahead.
The Indian Summer (or "gossamer") is a North American term for an unusually warm, sunny period after the summer season.
Here in Europe, the term "Indian Summer" has been borrowed from your side. Some might remember a successful song from the seventies, "L'été indien" (The Indian Summer):
Here's an English version:
About the song: https://en.wikipedia.org/wiki/L%27%C3%89t%C3%A9_indien