Heavy overnight rains lashed the city and its suburbs, prompting authorities to declare a holiday for schools on Monday. International flight operations at the airport were affected as around 10 incoming flights, including from Doha and Dubai were diverted to Bengaluru, subsequently affecting departure as well. Schools in various districts of Tamil Nadu will remain closed on Monday due to heavy rain, said the respective district administrations.Moderate thunderstorm with moderate rain is very likely in isolated places over Chennai, Tiruvallur, Chengalpattu and Kanchipuram districts for the next 3 hours (7 am to 10 am), said Regional Metrology Department, Chennai.