Anonymous
The author mentions the most likely indicators of a grid down: power is out, cell phone doesn’t work, land line dead, radios don’t work or has no stations on air, car won’t start. He also mentions the more severe stuff that may or may not happen: passenger jets falling out of the air, power line transformers blowing up, power line wires melting. If these last 2 happen, I expect that your unshielded appliances and electronics could catch fire and possibly your house could catch on fire.
I suppose the best way to be sure is to get one (you have more than one, right?) of your emergency radios out its emp shielded container and see what news you can get. Be sure to check the noaa weather stations and the shortwave frequencies too.