What causes Indian summer?

Answer 1

Stalled high-pressure wind currents create Indian Summers by:

High-pressure air pushing air towards areas with low-pressure, making wind. And because the Earth is spinning on its axis, the wind roatates counterclockwise about high-pressure zones.

Winds move south to north in the Northern Hemisphere, and north to south in the Southern. This creates Indian Summers all over the world (in the N. Hemisphere) like in New England and Europe, but for example, New Zealand gets this kind of weather (1 or 2 weeks of warmer weather) in April or May (S. Hemisphere). In the US, it's caused by the high-pressure air moving from the South West to the North East. EX: in New England, the warm air gets caught in the low-pressure areas by the coast and the weather becomes warmer until another low-pressure air current blows in, pushing the warm air out.

Answer 2

An Indian summer is typically caused by a period of warm, dry weather that occurs late in the fall season. This weather pattern usually happens when there is a shift in the jet stream, allowing warm air to move in and bring unseasonably high temperatures.