When is it safe to walk on a frozen lake?

[CFH]

Thanks for the replies chaps.

I've just been out there and as usual it is frozen solid. It is about -4'C out there today and the ice does look thick and set, but I'm not going to go on it. I will just stick to my exercise routine of walking around it.

There is no way I am ever going to be able to carry a cooker down there.

Not with that attitude.