Here we go, we're nearing summer's curtain call. After a midweek blast of lower humidity and fresh air, near record warmth returns on Friday, the last official day of summer. As that heat builds, there's a threat for severe thunderstorms in parts of southwestern Ontario on Thursday with heavy rain prompting warnings across cottage country. Expect widespread powerful wind gusts by Friday as a fall storm tracks across the north. More on the impact and big cool down that follows, below.