El Nino, weak monsoon behind Hong Kong’s warmest October in 142 years

Hong Kong sweltered through its warmest October on record, as an extremely strong El Nino, a weak northeast monsoon and a persistent anticyclone aloft over southern China combined to drive temperatures to unprecedented levels, the weather forecaster has said.

The Hong Kong Observatory forecaster said on Sunday that the mean maximum temperature for October was 30.5 degrees Celsius (86.9 Fahrenheit), the mean temperature 27.6 degrees and the mean minimum 25.8 degrees – all the highest for any October since records began in 1884.

“Aside from the impact of climate warming, we are experiencing an extremely strong El Nino event,” the forecaster said.

“Combined with a weaker-than-normal northeast monsoon last month and a stronger-than-normal anticyclone aloft over southern China, these were the reasons behind this record-warm October.”

The readings broke records set only a year earlier, when the mean temperature of 27.4 degrees and the mean minimum of 25.6 degrees were the highest ever logged for October.

This year’s mean maximum of 30.5 degrees also edged past the previous October high of 30.3 degrees, set in 2024.

The Observatory said on Saturday that the temperature at its headquarters climbed to 33.6 degrees on the afternoon of October 1, the highest of the month, due to weak winds and plenty of sunshine.

The mercury reached 32.3 degrees on the afternoon of October 23 at the Observatory, making it the hottest “Frost” solar term on record. The month’s coolest reading at the Observatory, 23.3 degrees on October 6, was also the lowest so far this autumn.