It is difficult to provide an exact figure for the average gas bill in Southern Ontario, as it depends on various factors such as the size of the house, insulation levels, thermostat settings, and energy efficiency of the furnace and other appliances. However, as a general estimate, an average house in Southern Ontario might pay anywhere between $50 to $200 per month on natural gas bills during the heating season. This range is based on data from previous years and typical household energy usage patterns. Keep in mind that these figures can vary significantly depending on individual household circumstances and energy consumption habits. To reduce your gas bills, consider improving your home's insulation, upgrading to energy-efficient appliances, and scheduling regular furnace maintenance with Martino HVAC to ensure optimal system performance.