Andrew Dessler hauls out the old dice metaphor for a helpful discussion of why one might take long term climate forecasts seriously even if those silly meteorologists can’t get tomorrow’s weather forecast right:
One simple way to think about the difference in predicting weather and climate is to think about rolling a six-sided die. Predicting the weather is like predicting what the next roll will be. Predicting the cliamte is like predicting what the average and standard deviation of 1000 rolls will be. The ability to predict the statistics of the next 1000 rolls does not hinge on the ability to predict the next roll. Thus, one should not dismiss climate forecasts simply because weather forecasts are only good for a few days.
As a side note, it’s worth noting that the very fact that people notice and remember blown weather forecasts is evidence for how good the meteorological community has gotten. The reason we get annoyed and remember when they get it wrong is that we’ve come to rely on them because, in general, over a few days’ time window, they usually get it right.