The city was engulfed by dense fog on Friday, bringing down visibility to 500 metres and leading to cancellation of 64 trains, officials said.According to the Northern Railway, due to thick fog in and around Delhi, 10 other trains were running late.The meteorological department has said the day is likely to be partly cloudy through out the day while fog is likely to return in the evening."There was dense fog in the morning. Sky is likely to be partly cloudy and the maximum temperature is likely to hover around 21 degree Celsius," an India Meteorological Department(IMD) said. The minimum temperature was recorded 9 degree Celsius, two notches above the season's average.On Friday, the humidity at 8.30 a.m was recorded 95 percent.Thursday's maximum temperature was 19 degree celsius, a notch below the season's average while the minimum temperate settled at 13.6 degree celsius, six notches above the season's average.