The Southwest Monsoon finally reached the capital on Tuesday, 16 days behind the usual date of onset, making it the most-delayed in 19 years, according to the India Meteorological Department (IMD).

In 2002, monsoon had covered Delhi on July 19.

"The monsoon has arrived in Delhi," senior IMD scientist K Jenamani confirmed after a spell of rains drenched parts of South Delhi Tuesday morning.

Normally, monsoon reaches Delhi by June 27. It covers the entire country by July 8. Last year, the wind system had reached Delhi on June 25 and covered the entire country by June 29.

The weather department had a tough time forecasting the advancement of monsoon over Delhi this year.

After several wayward forecasts, the IMD acknowledged Monday that "such type of failure by numerical models in the prediction of monsoon over the capital is rare and uncommon".

The IMD had earlier said monsoon would hit Delhi on June 15, which would have been 12 days early, but the wind system entered a "break" phase.

In early June, the Met office said the conditions will become favourable for the monsoon to advance to Delhi and other parts of northwest India by July 7.

Later, it said Delhi will get its first monsoon rains around July 10.

The weather department revised the forecast yet again on Saturday, saying the monsoon may reach the capital in the next 24 hours. But the wind system kept the city waiting on Sunday and there was hardly any rainfall on Monday too.

As monsoon played truant in the region, Central Delhi is now the most rain-deficient district in the country, receiving only 8.5 mm rainfall against the normal of 132 mm since June 1, when the monsoon season starts. It has recorded a shortfall of 94 per cent.

Overall, Delhi has so far received 67 per cent less rainfall than normal, putting it in the category of "large deficient" states.

The IMD said it is continuously monitoring the further progress of monsoon into the remaining parts of the country.