Heat wave!!!

It has been so hot here. Crazy hot.... we are talking 99 degrees yesterday and 96 degrees today. I like warm weather and everything but this is ridiculous. It has been so warm here that I have lost three koi in the last two days. One of them was over 20 inches long..... I had had it since it was about two inches in length...very sad. The heat has just come on so fast that there is just not enough oxygen in the pond. I am trying partial water changes on a daily basis to see if this will help. I have three water features but even that is not enough to keep them alive in this heat. RIP little fish.