The national capital witnessed a slight increase in temperature although a blanket of fog engulfed the city in the morning. The minimum temperature rose from Wednesday's 3.9 degrees to settle at 5.3 degrees Celsius, still two notches below normal. According to PRO of Northern Railways, 30 trains are running late due to fog. However flight operations at IGI Airport were not disrupted. The Met department predicts the night temperatures to increase in the coming days while the day temperatures are likely to fall down. Weathermen also expect light rainfall in a couple of days. Today will be a sunny day with mercury likely to oscillate between 19 and eight degree Celsius.