September 23 equinox marks the official end of summer in the UAE

Dubai: As the northern hemisphere prepares for the changing of the seasons, September 23 marks a significant astronomical event: the autumnal equinox. According to a latest detailed report from the National Center of Meteorology (NCM), this is when the sun is positioned directly perpendicular to the equator, signaling the official end of summer and the beginning of autumn. This celestial shift is more than just a date on the calendar; it says a gradual and welcome change in the UAE's weather patterns.

While the intense summer heat will linger through the first half of the month, the NCM's data shows that temperatures begin to decrease, particularly during the second half of September and especially at night. This is partly due to the gradual weakening of the Indian monsoon depression, which in turn gives way to the influence of desert thermal lows over the Arabian Peninsula. These lows can bring fresh winds that at times stir up dust, reducing horizontal visibility. However, for those living in the eastern parts of the country, there remains a chance of cumulonimbus cloud formation, which can be accompanied by rain and thunder. These rain clouds may even extend to internal areas, delivering varying intensities of precipitation.

The wind patterns themselves reflect this seasonal transition. Southeasterly winds are common during the late nights and early mornings, but as the day progresses, they shift to northwesterly winds due to the natural sea breeze and land breeze circulation. This circulation also plays a role in the slight increase in relative humidity, which averages at 49 per cent for the month.

This rise in humidity, especially in the second half of September, raises the chances of fog and mist forming in different parts of the country. Historical data shows that in June 2014, there were 14 occasions of fog and 12 misty days, highlighting how humidity can significantly impact visibility.

The NCM's climatic statistics for September provide a fascinating glimpse into the typical conditions and historical extremes. The mean air temperature ranges between 32.3 and 34.2 °C, with mean maximums hitting between 38.5 and 40.6 °C. The mean minimum temperature, however, offers some relief, ranging from 26.8 to 29.3 °C.

It's worth noting the historical extremes: the highest maximum temperature ever recorded was a sweltering 51.1 °C in Mukhariz in 2016, while the lowest minimum was a much cooler 16.5 °C at Jabal Jais in 2015. Wind speeds average around 11 km/h, but can be much higher during gusts, with the highest recorded wind gust at 109.3 km/h at Al Ain Airport in 2008. The highest rainfall recorded for September was 86.4 mm in Jabal Hafeet in 2006.