What does the Watchtower say?
‘What is wrong with going to a fortune-teller or reading your horoscope in a newspaper? Isn’t this just harmless fun?’ 
'The Bible does not treat the matter so lightly. In fact, it puts us on our guard against mediums and diviners. In the book of Deuteronomy, Jehovah gives the following warning: “In case a prophet or a dreamer of a dream . . . does give you a sign or a portent, and the sign or the portent does come true of which he spoke to you, saying, ‘Let us walk after other gods,’ . . . you must not listen to the words of that prophet or to the dreamer of that dream.”—Deuteronomy 13:1-3.' 
'Notice that the Scriptures do not question the fact that some of the predictions of mediums and astrologers may come true. Rather, the Bible warns us that, if these predictions are based on signs in the heavens or other methods of divination, they come from the demons, are deceiving, and may turn men away from the true God.—See Acts 16:16-18.' 
'To pay attention to astrologers or to others who claim to predict the future is to run the risk of incurring serious spiritual problems and ending up a slave of “the wicked spirit forces in the heavenly places.” (Ephesians 6:12) Thus, to consult such individuals is considered by God to be a serious sin; those who practice such things are detestable in his eyes and they will not inherit his Kingdom.—Revelation 22:15.' 
'It is thus for our own good that the Bible puts us on guard against astrology and all other forms of divination.'