According to the IMD, the Safdarjung Observatory, which is considered the official marker for Delhi, has received 1,159.4mm of rainfall this season till September 16 afternoon.
The bus was going to Mathura and got stuck at the underpass of Palam flyover, officials said.
Aviation Minister Jyotiraditya Scindia said on Twitter he spoke to airport officials and "was told that the waterlogged forecourt was cleared up within 30 minutes".
It has been a bountiful September for Delhi, with 343.6 mm of rainfall recorded so far this month, which is the highest in at least 12 years, according to data available on the IMD's website.
Delhi Traffic Police informed the carriageway of IOCL Dwarka To NSG Dwarka is closed due to waterlogging.
Normally, the capital gauges 247.7mm rainfall in August. The IMD had earlier predicted normal rainfall for Delhi this month.
Officials said the rain was heavy in parts of north and north-east Delhi, outer and outer north and west Delhi. South Delhi, too, saw traffic snarls for hours.
The Safdarjung Observatory, which provides representative figures for the city, recorded 26.1 mm rainfall.
The party said that Wednesday's chaos on roads exposed the poor functioning of the civic bodies which are responsible for cleaning and upkeep of the vast network of drains.
The underpass in South Delhi's Prahaladpur was severely waterlogged due to the rain and commuters were seen dragging their two wheelers through the knee deep water.
The IMD had on June 13 forecast that monsoon will hit nearly two weeks before its normal date of June 15.
Mahesh Palawat of Skymet Weather, a private forecasting agency, said the monsoon made a "weak onset" over Delhi and only patchy rainfall is predicted in the city over the next three days.
In early June, the Met office said conditions will become favourable for the advance of the monsoon in Delhi and other parts of northwest India by July 7.
The met office has been way off the mark in its monsoon forecast for Delhi this year.
Wind system may hit Delhi 13 days later than usual; light to moderate rainfall likely in NCR in next five-six days