Nothing in the Bible says that Satan is an angel (including a cherub, which is definitely a type of angel). However, the Bible *does* say this about Satan:
http://www.biblegateway.com/passage/?search=2co%2011:14&multilayout=cols&version1=49&version2=9
So: Satan can take on the **appearance** of an angel of light. Note also that the book of Job in the Bible *strongly* suggests that Satan is an angel, as it describes Satan as a being able to travel freely from Earth to the presence of God in Heaven.
Finally: Jesus teaches us this:
http://www.biblegateway.com/passage/?search=luke%2010:18&multilayout=cols&version1=49&version2=9
So:
- almost certainly Satan is (or "was," if you prefer) an angel
- Satan is *not* described as an "angel of fire" anywhere in the Bible, but he *can* **take on the appearance** of an "angel of light", which may seem similar
Note that several angels associated with fire *do* appear in the Bible.
- the burning bush that spoke to Moses, which was identified by the Bible as an angel
- the "angel of the Lord" who told Manoah and his wife about their future son Samson; he "ascended in the flame of the altar"
- cherubim (a "cherub" is a particular type of angel) alongside a flaming sword guarded the entrance to Eden after Adam and Eve were evicted
- Jim, http://www.bible-reviews.com/
P.S. I believe that - traditionally, not Biblically - Michael is associated with fire as he was described by tradition as wielding a flaming sword. The traditional (not Biblical) elemental assignments to the traditional 4 archangels are:
Michael - fire
Gabriel - air
Raphael - water
Uriel - earth