system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can you tell if a large body of water is frozen enough to walk safely on?

I'm thinking a lake or something like that.  I've never lived in an area where it snowed, and always wondered.
gpt
There's no surefire way to test it.  Most people who go out on frozen lakes do it annually and they just 'know' when the time is right.  And even they get it wrong sometimes.

For what it's worth, all it takes is a few inches of solid ice to support an automobile.  Corollary: all it takes is one feeder creek to make a weak spot, and people fall through.

In any situation where you're going to do this, always defer to the local residents.  If all else fails, you can call and ask the fire department for a recommendation.