Rain messed up the boys Day

How can you say sorry to kids these days. Well yesterday my grandsons wanted to go to the Beach and they wanted me to take them. Well that's not a problem except when they were brought to my house is had started raining. Let's see about an half hour later the Sun came up. So now I figured we are good to go. On the way there guess what is started to rain again but I told the boys we would still go. Upon arriving about 5 miles from the beach the weather got worst. I mean the winds were blowing as if there had been an hurricane had past of close by. Then I took a look at the water and if was to rough for the boys to be in so we turned around and when back to my house for a few before they were suppose to go home. I will have to take them another day now due to the weather but how can you say sorry to them for what happened when it is not your fault. Don't get me wrong they understood the weather thing but when they are 5 and 7 you know they have alot of questions.