Cedar trees can live 30 to 60 years depending on their species.
Lack of nutrition or water, disease, age and extremely harsh weather conditions can cause your cedars to die. When your cedars stop producing green, healthy branches and are dry and permanent browny-red in colour, your cedars have died.
Parts of the cedar may naturally turn a browny-red/golden colour in hot conditons or during cold winters, but will regain their full green look throughout the spring. As your cedars age they may naturally lose a few branches which is no cause for concern.
Be sure to water, feed and prune your cedars to keep them in excellent growing condition.