Indian summer

American  

noun

1. a period of mild, dry weather, usually accompanied by a hazy atmosphere, occurring usually in late October or early November and following a period of colder weather.

---

Indian summer British  

noun

1. a period of unusually settled warm weather after the end of summer proper

2. a period of ease and tranquillity or of renewed productivity towards the end of a person's life or of an epoch

---

Indian summer Cultural  

1. A period of unusually warm weather in the fall, often following a seasonable cold spell.

---

Indian summer Idioms  

1. A period of mild, sunny weather occurring in late autumn, usually following a seasonable cold spell. For example, We had two whole days of Indian summer this year, and then it turned cold again. [Late 1700s]

---

Etymology

Origin of Indian summer

An Americanism dating back to 1770–80

Example Sentences

Temperatures will stay around average until the weekend when it will turn a little warmer but will a September heatwave lead to a so-called Indian summer?

From BBC • Sep. 1, 2025

Many people lined polling stations before the start of voting at 7 a.m. to avoid the blazing sun later in the day at the peak of Indian summer.

From Seattle Times • May 24, 2024

But I'll never forget that one hot Indian summer.

From Salon • Jul. 16, 2022

He has enjoyed an Indian summer of sorts ever since he switched trainers to Hall of Fame fighter turned coach Buddy McGirt this year.

From Los Angeles Times • Sep. 13, 2019

At last, after September, another weather arrives, an Indian summer that occasionally endures until Christmas.

From "In Cold Blood" by Truman Capote