Thunder and Lightning
When I was a teenager I earned spending money by working as a lifeguard during the summer. It’s a pretty cushy job most of the time. Who doesn’t want to spend hot days right by the pool? Any time it got too warm, I just jumped in the water to cool off.
The only times we had to shut down the pool were for thunder and lightning. Since we didn’t want to get electrocuted our policy was to wait 30 minutes after the last thunder was heard or the last lightning was spotted before we’d let patrons back in the pool. I use that policy now whenever I go boating. I don’t want to get stranded on the water during a storm, so I use the time ashore to teach my kids about 2 stroke oil and other boating necessities.