weather is different than climate. weather is short term climate is long term. Yes, weather can not be predicted very far ahead. Climate, however, can be SOMEWHAT predicted. Emphasis on somewhat because these predictions are not very accurate because we have no perfect or near perfect models of the earths systems. Things like el nino or la nina can be predicted in advanced but there is no telling how long the trends will last or how strong the trends will be. It is still a lot of guesswork but they can predict general trends fairly far out