一、前言北京冬期约四个月,由11月中旬至3月中旬。近11年(71～82)极端最低气温为-18.30℃,一般出现在一月下旬,其旬最低气温平均值为-9.19℃。严冬期一般为50天(12月下旬至2月上旬)。此间月平均气温为-4.7℃。最低气温持续时间不长,出现正负温度交替天数,约占全冬期天数的80％。 I. Preface The winter period in Beijing is about four months, from mid-November to mid-March. In the past 11 years (71-82), the extreme minimum temperature was -18.30°C, which generally occurred in late January. The average minimum temperature in the ten days was -9.19°C. The winter period is generally 50 days (late December to early February). The average monthly temperature here is -4.7°C. The minimum temperature lasted for a short period of time, with alternating days of positive and negative temperatures, accounting for about 80% of the total winter days.