Chennai may have an extended northeast monsoon this year as the Meteorological Department forecasts one more spell of heavy rain after Christmas.

Officials of the department said usually the monsoon withdraws around December 20 in the northern parts of the State, including Chennai. However, this year, the weather models show that there may be an increase in rainfall over coastal districts of the State during the last week of this month.

Though the minimum temperature has been dipping for the past three days, the monsoon is still prevailing in the coastal districts. The southern parts of the State are experiencing isolated rainfall.

On Monday, the observatories in Nungambakkam and Meenambakkam registered a minimum temperature of 20.7 degree Celsius and 20.5 degree Celsius, which is one degree below normal. The observatories recorded humidity of 57 per cent and 61 per cent respectively.

Some of the weather stations in the State as in Tirupattur have already recorded a minimum temperature of 16 degree Celsius. In the past decade, the lowest minimum temperature in Chennai was 18 or 19 degree Celsius, the officials said.

The department forecasts light rain in some areas on Tuesday.