The '30 Seconds to a Mile' Thunder Trick You Learned as a Kid Is Slightly Wrong

Counting between lightning and thunder does work — but the math most of us memorized is off.

Everyone learned it at a sleepover: see the flash, count the seconds, and every count is a mile. Cute, memorable — and wrong. The internet is currently discovering the real math, and some people are genuinely rattled by how close their storms have been.

Sound travels roughly a mile every five seconds. So that storm you counted 'five miles away' as a kid? It was one mile away. The flash-to-boom method works; the exchange rate was just badly off.

The rule meteorologists actually want you to remember is even simpler: if you can hear thunder at all, lightning is close enough to reach you, so head inside. Counting is for curiosity, not for deciding whether to keep grilling.

The comment sections are a delight: 'I've been narrating storms confidently and incorrectly for 30 years.' Same. We all have. Five seconds per mile — pass it on.