an Indian summer
1. A period of unseasonably warm weather in early fall. I know it's September, but don't get out your winter clothes just yet—this area often has an Indian summer. I hate the cold weather, so I'm hoping for an Indian summer.
2. A particularly peaceful, successful, or enjoyable time as something nears its end. As her illness worsened, my grandmother still enjoyed painting, so I think she had an Indian summer before her death. I wonder if people sensed that they were in an Indian summer just before the Great Depression.
an Indian summermainly BRITISH
An Indian summer is a period of great success late in someone's life or career, often after a period of not being successful. Despite an unexpected Indian Summer, they never really lived up to their initial promise. Note: An Indian summer is a period of unusually warm sunny weather during the autumn.
an ˌIndian ˈsummer
1 a period of unusually dry, warm weather in the autumn: We had a splendid Indian summer last October.
2 a period of success or happiness near the end of somebody’s life: He made his best movies in his seventies; it was for him a real Indian summer.