New Delhi, Sep 22 (PTI) An incessant spell of light to moderate rain drenched Delhi for the second consecutive day on Thursday, leading to waterlogging in several areas and affecting traffic movement on key roads across the city.The India Meteorological Department (IMD) also issued a "yellow alert", cautioning people about moderate rain at most places in the city on Friday.The Palam Observatory reported heavy rain -- 81 mm between 8:30 am and 8:30 pm.Rainfall recorded below 15 mm is considered light, between 15 and 64.5 mm is moderate, between 64.5 mm and 115.5 mm heavy, between 115.6 and 204.4 very heavy. Anything above 204.4 mm is considered extremely heavy rainfall.The fresh spells of rains just before the withdrawal of monsoon from the National Capital Region will help cover the large deficit (46 per cent till September 22 morning) to some extent. It would also keep the air clean and the temperature in check.   The city recorded a minimum temperature of 23.8 degrees Celsius and a maximum temperature of 28 degrees Celsius, seven notches below normal.The 24-hour average air quality index settled at 66 (satisfactory category) at 4 pm, improving from 109 on Wednesday.The Safdarjung Observatory, Delhi"s primary weather station, gauged 31.2 mm of rainfall between 8:30 am and 5:30 pm.The weather stations at Lodhi Road, Ridge and Ayanagar received 27.4 mm, 16.8 mm and 45.8 mm of precipitation during this period.The Delhi University area, Jafarpur, Najafgarh, Pusa and Mayur Vihar recorded 16.5 mm, 18 mm, 29 mm, 24.5 mm and 25.5 mm of rainfall, respectively.The Safdarjung Observatory has recorded 58.5 mm rainfall against a normal of 108.5 mm in September so far (till Thursday morning).It had recorded 41.6 mm rainfall in August, the lowest in at least 14 years, due to the absence of any favourable weather system in northwest India.Overall, Delhi has recorded 405.3 mm rainfall against a normal of 621.7 mm since June 1, when the monsoon season historically sets in.The IMD on Tuesday said the southwest monsoon had withdrawn from parts of southwest Rajasthan and adjoining Kutch, three days after the normal date of September 17.Usually, it takes around a week after its withdrawal from west Rajasthan for the monsoon to retreat from Delhi.The withdrawal of southwest monsoon is declared if there has been no rainfall in the region for five days along with the development of anti-cyclonic circulation and water vapour imagery indicates dry weather conditions over the region. PTI GVS TDS TDS