Patna, Oct. 19: At a time when most of Bihar’s districts have been declared drought hit, the stay of southwest monsoon this year in the state has been the longest in the past 10 years.

The monsoon officially retreated from Bihar today, 11 days after its normal withdrawal date of October 8. In fact, some areas experienced rainfall till yesterday, which the weathermen attribute to the remaining moisture content of cyclone Phailin.

The all India weather bulletin of India Meteorological Department (IMD) on Saturday afternoon stated that the southwest monsoon withdrew from entire Bihar, Jharkhand, Chhattisgarh, Vidarbha, Marathawada, most parts of Odisha, central Maharashtra and Konkan and some parts of Gangetic West Bengal, Telangana, north interior Karnataka and central Arabian sea.

Prolonged monsoon apart, the present weather conditions in Patna also seem to be paving the way for an early onset of winter.

Meteorologists say that only a minimal percentage of the high level of moisture that was brought into the atmosphere of Bihar by cyclone Phailin still remains and cooler and dry north-westerly winds have begun blowing over the city from yesterday.

Talking about the delayed withdrawal of southwest monsoon, Ashish Sen, director, IMD-Patna, told The Telegraph: “Although southwest monsoon normally withdraws from Bihar by October 8, this year it withdrew only today. As per observation, it is the longest duration of stay of southwest monsoon in Bihar and its neighbouring regions.”

The rain-bearing winds had entered Bihar on June 15 and the rainfall across the state during the monsoon season (June 1 to September 30) was the lowest in the past 10 years. The state received 723mm of rainfall against the normal of 1,024mm during the four months of monsoon, which was 30 per cent deficient.

IMD had earlier predicted monsoon withdrawal by the first week of October. IMD-Patna chief Sen claimed that the delayed withdrawal of southwest monsoon in the country mostly depends on weather conditions in the southern hemisphere. “The exact reason behind the delay in withdrawal of the southwest monsoon requires a detailed assessment, which would be done by the IMD over the next few weeks,” he said.

Sen did not rule out the impact of Phailin in delaying the withdrawal of monsoon in the region.

The record drop in temperature in Patna for the month of October was observed when Phailin hit Bihar last weekend. The maximum temperature on Tuesday — a day after the heavy rainfall had stopped — in Patna was 25.1 degrees Celsius, which was seven degrees lower than normal and the lowest maximum temperature for the month of October in the past 10 years. The mean maximum temperature for October is 31.5 degrees Celsius.

Though there is a gradual surge in the mercury column, weathermen say the temperature would start dipping in the city over the next few days.

“Cooler mornings and nights would be observed in Patna from now on. The lifting of moisture and initiation of north-westerly winds would also lead to a gradual drop in the day temperature over the next few weeks,” said Sen.

Winter is said to set in when the minimum temperature continues to remain below 13 degrees Celsius for around a week.

Sen said a fall in temperature in the monsoon season is mainly triggered by the impact of western disturbance in a region.

“A total of four western disturbances have formed in the Indian sub-continent as of now but all of them passed around 35 degree latitude, near Jammu and Kashmir. It must pass through around 30 degree latitude to trigger a drop in temperature in Bihar and Patna,” said Sen.