Core Viewpoint - The onset of winter has been perceived earlier this year in northern China, particularly in Shanxi province, due to a significant drop in temperatures and continuous rainy weather since October, leading to early heating supply in Taiyuan [1][4]. Group 1: Weather Conditions - Northern regions of China, including Shanxi, have experienced continuous rainy weather and a sharp decline in temperatures since October [1]. - Taiyuan began its heating supply on October 19, more than ten days earlier than the same period last year [1]. - The minimum temperature in southern Beijing dropped below freezing on October 20, prompting public comments about an abrupt transition to winter [1]. Group 2: Meteorological Definitions - The term "入冬" (entering winter) is defined meteorologically as the first day when the sliding average temperature falls below 10 degrees Celsius [3]. - "立冬" (Beginning of Winter) and "冬至" (Winter Solstice) are traditional solar terms, with "立冬" fixed around November 7 or 8, and "冬至" marking the shortest day of the year [3]. Group 3: Perception of Cold - Residents in Taiyuan report feeling a stark cold, with comments on the biting wind and sudden temperature drop [4]. - Meteorological experts indicate that while some areas may feel like winter has arrived, actual winter conditions are not met in Taiyuan, where temperatures are expected to remain above 10 degrees Celsius in the coming days [5]. - The discrepancy between perceived and actual temperatures is attributed to factors such as wind speed, humidity, and sudden changes in weather patterns, leading to a psychological feeling of "winter" despite meteorological definitions [6].

而根据节气划分的四季中，冬季，以立冬为起点，冬至为中点，终点在立春前。立冬日期基本固定在每年的11月7日或者8日。冬至，俗称"数 九"，这一天太阳照射北半球时间最少，白天最短。 新华社太原10月21日电（记者樊欣阳、柴婷）10月以来，北方多地出现连阴雨天气，气温直线下降。为应对连续低温，山西太原19日开始提前供 暖，比去年同期早了10余天。北京南郊观象台20日最低气温跌破冰点，一些网友表示，今年感觉像是"一秒入冬"。 10月19日，工作人员在太原市集中供热调度中心监测供热情况。新华社记者 杨晨光 摄 入冬、立冬、冬至有啥区别？ "上一秒"还秋高气爽，"下一秒"就火速"入冬"，难道冬天真的来了？入冬、立冬、冬至，听起来好像都是迈入冬天的信号，它们有啥区别？ 山西省气候中心正研级高工刘月丽解释说，气象学上的入冬，是指按照气象学标准进入冬季的意思，而立冬、冬至均是二十四节气之一。从气象 学上来说，是以温度来划分四季。以当年5日滑动平均气温稳定降到10摄氏度以下时，第一个小于10摄氏度的日期作为冬季的开始。 不论如何，虽然有些地区气象意义上的冬天还未正式"报到"，但寒冷的感觉已然真实。大幅降温容易引发心血管类和呼吸系 ...