1. Overall climate of September
Temperature
In September, Beijing's average monthly temperature (the average from 1981 to 2010, the same below) is 19.0℃. Temperatures will start to drop after September. The average temperature in the first ten days of September is 21.1℃, but when it comes to the second ten days, temperatures will get below 20℃, with the average of the second and third ten days of September being 19.1℃ and 16.9℃.
According to Beijing Observatory, Beijing's extreme maximum temperature reached 35℃ on September 1, 2002, and the extreme minimum temperature was 3.7℃ on September 28, 1968.
Precipitation
In September, Beijing's average monthly precipitation is 53.3 mm. As the time is the end of summer and the beginning of autumn, severe convective weather is still likely. According to Beijing Observatory, between 1951 and 2017, there were 9 Septembers with a heavy rainfall (daily precipitation≥50mm), the maximum daily precipitation being 106.0 mm on September 2, 2014.
Table 1. Meteorological Elements of Beijing in September
Time Elements September 1-10 Sept 11-20 Sept 21-30 Sept Average temperature (℃) 19.0 21.1 19.1 16.9 Extreme maximum temperature (℃) 35.0 (2002-09-01) 35.0 (2002-09-01) 34.4 (2000-09-16) 32.5 (1996-09-22) Extreme minimum temperature (℃) 3.7 (1968-09-28) 7.7 (1967-09-10) 5.5 (1974-09-17) 3.7 (1968-09-28) Precipitation 53.3 21.6 17.4 14.3 Maximum daily precipitation (mm) 106.0 (2014-09-02) 106.0 (2014-09-02) 83.5 (1958-09-14) 73.9 (1961-09-28)
Note:
(1) The average temperatures and precipitation are the average of statistics from 20 national-level meteorological observing stations in Beijing.
(2) The extreme maximum and minimum temperatures and the maximum daily precipitation are extrema recorded by Beijing Observatory since 1951.
2. High-impact weather events
Gale: For September's Beijing, the average number of days of strong wind is 0.2 day. The maximum was 3 days in 1959.
Fog: According to Beijing Observatory, for September's Beijing, the average number of foggy days is 1.3 days, with the maximum being 6 days in 1955.
Heavy rainfall: According to Beijing Observatory, between 1951 and 2017, there were nine Septembers with a heavy rainfall (daily precipitation≥50mm), the maximum daily precipitation being 106.0 mm on September 2, 2014.
High temperature: According to Beijing Observatory, between 1951 and 2017, there was only one September with high temperature (≥35℃), and it was only for one day on September 1, 2002. (The temperature was 35.0℃.)
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