Forecast

WEATHER OUTLOOK (16 – 30 SEPTEMBER 2025)

1    The prevailing Southwest Monsoon conditions are forecast to persist over Singapore and the surrounding region for the rest of September 2025, with winds blowing mainly from the southeast or southwest.

2    In the second fortnight of September of 2025, Sumatra squalls may bring widespread thundery showers and gusty winds in the pre-dawn and morning on several days. Localised short-duration thundery showers can be expected over parts of the island on some afternoons. There may be few dry days. Overall, the total rainfall for the second fortnight of September 2025 is forecast to be near average over most parts of the island.

3    Daily temperatures are likely to range between 24 degrees Celsius and 33 degrees Celsius on most days. Although thundery showers are expected on most days, the daily maximum temperature may reach slightly above 34 degrees Celsius on a few days.

4    For updates of the daily weather forecast, please visit the MSS website (https://www.weather.gov.sg), NEA website (www.nea.gov.sg), or download the myENV app.

REVIEW OF THE PAST TWO WEEKS (1 – 15 SEPTEMBER 2025)

5    In the first half of September 2025, Southwest Monsoon conditions prevailed over the region and the low-level winds blew mostly from the southeast or southwest.

6    In the first half of September 2025, localised short-duration thundery showers fell over parts of the island on some days. Sumatra squalls brought thundery showers over Singapore in the pre-dawn and morning on several days. On 5 September 2025, the passage of a Sumatra squall brought widespread thundery showers and gusty winds over Singapore in the morning. The daily total rainfall of 102.6 mm recorded around the Sarimbun Reservoir area that day was the highest rainfall recorded for the first half of September 2025.

7    The rainy weather and cloudy skies in the first half of September 2025 brought relatively cool conditions on several days. There were four days in the fortnight where the daily maximum temperature was below 30 degrees Celsius. The highest daily maximum temperature of 33.8 degrees Celsius was recorded at Admiralty on 3 September 2025.

8    Singapore registered well above-average rainfall in the first half of September 2025. The area around Seletar recorded 248 per cent above average rainfall while Paya Lebar recorded rainfall of 73 per cent above average.

CLIMATE STATION STATISTICS

Long-term Statistics for September
(Climatological reference period: 1991 – 2020)

Historical Extremes for September
(Rainfall since 1869 and temperature since 1929)