The mercury settled at a pleasant 12.3 degrees Celsius in the national capital today, even as foggy conditions hit operations at Indira Gandhi International Airport here and delayed several Delhi-bound trains. <br/><br/>At least 54 Delhi-bound trains were running behind schedule by two to four hours due to reduced visibility and 11 trains were canceled. According to the Delhi airport website, more than 38 domestic and international flights were affected, of which around 8 were canceled.