Yesterday saw the end of a sustained period of heat for many, with thunder and lightning marking the beginning of fresher conditions. In Sydney temperatures dropped like a stone as the change moved through, with Mascot cooling 11 degrees in 10 minutes and Observatory Hill cooling 5 degrees in 15 minutes. Thunderstorms also rolled through from around 2pm, with over 17,000 lightning strikes within 50km of Penrith between 2pm and midnight. Of these, just over 2600 reached the ground. Not only did these storms put on a light show, they also help cool the city around a further 10 degrees, down into the low 20's. Cooler conditions lie ahead for the city for a couple of days, which below average for the time of year and after the recent heat, could feel a little chilly. Those warm days aren't far away though with the mercury set to climb again middle of next week.