I found this during the last heatwave. Con Ed has this great application on it's website, which you can access here. It is updated every half hour, and it seems to be very accurate. Make sure to check the zoom feature as well, and you'll be able to see exactly where the outages are. With yet at least one more day left to this heatwave, you never know when it may come in handy. So far, this season, I'd give Con Ed a grade of A-, but there is plenty of long, hot summer to come.