How Often Does This Happen in Portland?

Saturday we rode our bikes to the Farmer's Market and CJ almost melted. On Sunday we decided we needed to find a spot with water so we rode our bikes to Sellwood Pool. We had a lot of fun and were sitting on the side of the pool for a break and snack when we heard thunder. The lifeguards promptly cleared the pool and asked everyone to leave the pool deck. The plan was to wait for 30 minutes and possibly reopen, but more thunder was heard so they ended up closing the pool for the day. They did hand out free passes so I'm sure we'll head back again.