Everything else aside, I was living in northern New Jersey at the time. Strange as it may sound, weirdly detached perhaps but I will never forget how incredibly blue the sky was that day. I’d never seen anything like it, before or since. It made it all the more... horribly surreal, the smoke and flames seemed so stark against that blue sky. Prayers for all who were murdered that day.
Pilots call a day like 9/11/01 "severe clear". --- Not a cloud or hint of haze in the sky. Nothing but bright, blazing sun.