When it will start getting cooler depends on the location, but generally, in many temperate regions, it starts to get noticeably cooler in late September to early October. For example, in some areas, nights begin to cool significantly by late September, while daytime temperatures may still be warm, with more consistent cooling by November. Seasonal patterns such as La Niña can also influence the timing, sometimes leading to warmer starts in autumn but cooling by December in certain regions.

If the location is known, a more precise forecast can be obtained using real- time weather data based on that location. Would it be possible to provide the current location or region of interest? This will help in giving an accurate answer on when it will start getting cooler there.