The best month for camping in Ontario, Canada, is typically July. During this time, the weather is warm and comfortable, with temperatures ranging from 60°F to 80°F. June and August are also good months for camping in Ontario, as the weather is still pleasant and there's plenty of daylight for outdoor activities. However, be prepared for occasional rain showers and mosquitoes during these months. Keep in mind that the weather can vary across the province, so it's essential to check the specific region you plan to visit for more accurate information.