St. Thomas, Ontario is sweating through a hot and sunny Wednesday, but residents should keep an eye on the sky as a risk of thunderstorms moves in for Thursday.
According to Environment Canada, the temperature hit 28.2°C by late afternoon on August 5, 2026, feeling more like 32 with the humidity. The sun stayed bright with just a light breeze from the south-southwest.
No weather alerts are currently in effect for the St. Thomas area. However, the forecast for Thursday, August 6, calls for a mix of sun and cloud, a high of 29°C, and a humidex that could climb to 37. There is a 40 percent chance of afternoon showers and a risk of thunderstorms.
Thursday also brings a very high UV index of 9. Health Canada advises that when the index is this high, people should limit time in the sun, especially between 11 a.m. and 3 p.m. Officials recommend wearing UV protective sunglasses, staying in the shade, and reapplying sunscreen every two hours, or after swimming or sweating.
This kind of summer weather is typical for the region. The normal high for St. Thomas in August is 26°C, with a low of 16°C. The day will also be long, with sunrise at 6:20 a.m. and sunset not until 8:41 p.m.
Looking ahead, the thunderstorm risk fits a pattern for southwestern Ontario, where warm surface air mixing with cooler air above can create unstable conditions. These can sometimes produce funnel clouds, especially near Lake Huron. Residents planning outdoor activities on Thursday should stay tuned to local forecasts and be ready to move indoors if storms develop.
