The Radar image I showed at 11 PM tonight. Note the heat advisory around Philadelphia.

So, why such a small Heat Advisory?

Look at the temps. at 11 PM EDT Monday night:

Note the temps. in Central Philadelphia and Wilmington are around 6-10 degrees F. warmer than the surrounding areas. Yes it’s the urban heat island effect, and Philly has a big one.The extra heat pushed Philly beyond the criteria for a Heat Advisory, while areas away from the city were not hot enough. You may have heard the myth floating around that humans could not possibly have an effect on the weather, but this is patently absurd. Not only are we doing so, it’s going to cost cities a lot of money as the planet warms (Nature Climate Change paper here.). It’s also costing the residents more money to keep cool.