How often does the weather ruin something you were looking forward to?

We will not be able to see the eclipse here in New York, and we will probably not be able to see the blood moon because they are predicting rain for tonight.  

Same here. I missed a major full solar eclipse in Virginia because of rain. My wife recorded it.

 

  Over 24 hours before the lunar eclipse was supposed to be viewable in Southern California (approximately 4:15 am), I was planning to post a question here to see if others would be getting up to see it in person as opposed to watching a broadcast of it. I forgot to post it, but I did get up at 3:50 am and went outside several times over the next 20 minutes, only to be met with extremely cloudy skies. (Sigh.)

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Very rarely.  I've never been willing to accept weather for changing plans. 

Apart from cloud cover blocking views of astronomical events, which is disappointing...

I can't really think of any events "ruined" for me by bad weather. Spoilt, yes, most often by rain; but most of the time now I take the weather as it comes.

The worst I have endured was 36 hours of strong winds and lashing rain while camping on a fairly remote Norwegian hillside. The spoiler was not really the weather, even though that was very unpleasant. Instead it was that my tent leaked badly. Luckily we returned to the road next day, the weather cleared and I was able to dry everything. Except my camera and the film it contained (pre-digital) - that was the only real loss.