Some historians suggest a darker origin. During the dry, windy conditions of late autumn, the risk of forest fires was high. These fires were often started by Native Americans clearing land for hunting or signaling, creating a smoky haze in the air. Thus, the term referred to the specific atmospheric conditions created by these fires.

Another theory suggests that the weather was considered "fake" or deceptive. Just as settlers called corn "Indian corn" to distinguish it from the corn they knew in Europe, they may have called this false summer "Indian Summer" to indicate it was not a "true" summer, but an imitation.

An Indian Summer is usually caused by a shift in the jet stream. A high-pressure system moves in from the south or southwest, pulling warm air from the Gulf of Mexico or the desert Southwest up into the northern states. This blocks cold Arctic air from moving south for a few days, resulting in sunny skies and unseasonably high temperatures.

This depends on context and audience. Many meteorologists and dictionaries still use “Indian summer” neutrally, but some style guides and indigenous advocacy groups recommend alternatives because the term is rooted in ethnic stereotyping. If you’re writing for a broad or sensitive audience, better options include:

So, what makes Indian Summer so special? Here are some key characteristics: