18 ms·

Put a bottle water in the freezer until it's frozen. Turn it on it's side. If you notice the ice-air line isn't vertical, you had a warming event.

• ndjskska 7y ago
  There are heat-sensitive stickers that change color if above some threshold. It's on packaged meat in Norway I believe.
  • roland35 7y ago
    that would be a good single use solution, we generally only a long power outage once every few years so that could work.