The start of colder weather varies by location, but generally:
- In many parts of the United States, particularly the Midwest, the temperature begins to drop noticeably by mid to late September, with chilly fall-like air becoming more prevalent by late September or early October. This chill can linger and deepen through the fall and winter months. For example, cities like Minneapolis and Chicago experience temperatures dropping into the upper 50s to 70 degrees around this time, with colder temperatures arriving by November and the deepest cold winter months in January and February. The cold weather season typically lasts through March with warming beginning in April.
- In the UK, temperatures start to decline around October, dropping to average daily maximums of about 12°C compared to 16°C in September, with the coldest period running from December through February. The cold usually eases off in March as spring approaches.
- The exact timing depends greatly on specific geographic and climatic conditions, but it can be expected that colder temperatures will start to become noticeable between September and October in many temperate regions.
If the exact location is provided, more precise timing can be given. Overall, this period marks the transition into colder weather in the Northern Hemisphere for most temperate areas.
