IF you have been feeling the chill in your bone and reaching for your woollies, blame the weather.

Average temperatures so far this month have dipped to 25.6 deg C - the lowest in 74 years. The coldest March was in 1934, when mean temperatures was 25 deg C.

Thermometers across the island registered a chilly 21.8deg C - cooler than most air-conditioner temperatures - on Thursday night, making it the fourth coldest day since 1934.

Prolonged heavy rain and dense cloud cover have caused surface temperatures to cool, said Associate Professor Matthias Roth from the National University of Singapore's Department of Geography.

'It's more difficult for sunlight to penetrate the thick cloud cover - so the ground cools after a few days,' he explained.

The freakishly wet weather is also due to a strong La Nina effect over the Pacific Ocean, explained Dr Roth. Caused by a cycle of cooling over the ocean, the weather phenomenon usually results in cooler, wetter weather.

Global climatologists estimate that the current La Nina cycle began last year and is expected to continue throughout the year.