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Monthly Forecast

Monthly Forecast for September 2026


Hong Kong is expecting:
1.
 normal to above-normal temperature
2.
 normal to below-normal rainfall



Additional information:
  1. Broad troughs of low pressure are expected to bring unsettled weather to the central and northern parts of the South China Sea in the first half of September 2026, favouring areas of low pressure and tropical cyclones appearing over the region.
  2. The anticyclone aloft covering southern China and the northern part of the South China Sea will gradually strengthen in the latter half of September. Temperatures over southern China are expected to be normal to above-normal in the month.

Assessment (as of 31 August 2026):
  1. In the past month or so, the sea surface temperatures of the central and eastern equatorial Pacific continued to rise significantly and stayed above normal. Based on the latest oceanic observations as well as forecasts by a number of climate models around the world, the warming trend in the central and eastern equatorial Pacific is expected to continue. The situation is forecast to develop into an El Niño event in late summer and persist at least until spring next year. It is expected to strengthen into a very strong event and peak around November and December this year, with a chance of becoming the strongest El Niño event on record since 1950.

  2. Taking into consideration of the impacts of global warming and latest ENSO status, different climate model forecasts and other objective forecast guidance, the temperature of September 2026 in Hong Kong is expected to be normal to above-normal, and the chance of normal to below-normal rainfall in the month will be slightly higher.


Note:
  1. The Observatory gratefully acknowledges the European Centre for Medium-Range Weather Forecasts, the Tokyo Climate Center of the Japan Meteorological Agency and the National Centers for Environmental Prediction of National Oceanic and Atmospheric Administration, USA for providing dynamical prediction model forecast and hindcast data to support the formulation of monthly forecast for Hong Kong.

  2. Monthly Forecast for October 2026 will be available around 1st October 2026.

  3. Monthly mean temperature and rainfall categorical forecasts charts.

  4. Ten days constitute a "ten-day period," and three such periods make up a month. The first ten days of each month are called “the first part of the month”, the second ten days are “the middle part of the month”, and the remaining days are referred to as “the latter part of the month”.

 
Monthly forecast charts provided by major climate centres:
Related links:
| Seasonal forecast | Annual outlook | El Niño and La Niña | Climate change |
For further information on this webpage, please contact Mr. W P Tse (tel:2926 8012, email:wptse@hko.gov.hk)