If the hair melts off your head, you're too close.
Twice I've been within 15m of ground strikes. Fortunately, they missed. One hit the truck beside me in a parking lot, and the other hit the bridge I was driving across at the time. With the bridge strike I had my window down. My ears rang for a while after that.
The bang hits you before your brain has processed the flash.
I've also been on aircraft when they were struck, once over Pakistan and once over the US. I don't care to repeat that.
That is four strikes
way too close. Don't stand near me in a storm
Eric