Here's a good commentary by Matthew Curie: Does The Bible Condemn Astrology?
Highlights:
Although there are verses in Genesis, Judges, and Luke that appear to support astrology (and most famously, the Book Of Matthew, where the Wise Men appear to use astrology to find the Messiah), I'm going to focus on the ones that appear to disapprove of astrology.
Deuteronomy 17:3
Among a list of other things God finds abominable are people who "...hath gone and served other gods, and worshiped them, either the sun, or moon, or any of the host of heaven, which I have not commanded." This one gets used a lot to condemn astrology. The problem with that is that astrologers don't "worship" the Sun or Moon any more than truck drivers "worship" road maps or meteorologists "worship" Doppler radar maps of storm cells. I also apply this viewpoint to Zephaniah 1:4-5 ("I will cut off ... them that worship the host of heaven").
Isaiah 47:13-14
"Let now the astrologers, the stargazers, the monthly prognosticators, stand up, and save thee from these things that shall come upon thee. Behold, they shall be as stubble; the fire shall burn them; they shall not deliver themselves from the power of the flame: there shall not be a coal to warm at, nor fire to sit before it. "
Well, that seems pretty straightforward...until you look at the context. Isaiah 47 is about God's anger with Babylon. Once you read the whole thing, it's obvious that what we're looking at here is not a specific condemnation of astrology or divination—it's a warning that God is going to do what God is going to do, according to His will and His timetable... not yours or anyone else's. 
A modern version of this might be something like "I don't care how healthy you are, or what the actuarial tables say about your lifespan, or how organic and unprocessed your diet is... if God wants you to drop dead of a heart attack next Tuesday, that's what's going to happen."
- end -
In short, when reading Bible verses, it's always best to get into the context.
WHAT IS ASTROLOGY?
Astrology is simply the study of cycles and seasons. If you know the season for rain, you would know when best to plant.
