Etymology of the Months
January - The month of January is named from the Roman god, Janus. Janus was the keeper of the gates of Heaven and he had two faces. The one at the back represented the old year and the one at the front represented the new year. Hence the month is the first month of the new year. There is, however, a St. Januarius San Genarro, who is the patron saint of Naples, Italy, but the month is not known to be named from him.
February - Februaria is the name that Juno (or Hera, according to the Hellenic mythology) was given as the goddess of fertility. February is named after the Latin februum which means purification. The Februa ceremonies were held on February 15th in the old lunar Roman Calendar. January and February were added last to the Roman calendar. This was because winter was originally the monthless period. A man by the name of Numa Pompilius in around 713 BC added them to the calendar. February remained the last month of the calendar year, until about 450 BC, when it became the second month.
February originally had 29 days, but the Romans took one from it to give it to July so that it wouldn't be inferior to August!
March - In the old Roman days, March was the first month of the New Year. March is named from the Roman god of war, Mars.
April - The Romans named April after the flower buds that open, from the Latin word aperia, which means opening.
May - May may have originally gotten its name from Maia, the goddess of Spring and fertility or to honor the Maiores, the early Roman Senate.
June - According to one theory, one of ancient Rome's leading class, the Junius family, had a month named after them. The poet Ovidio also says that the month is named from the goddess Juno, who is also the goddess of marriage.
July - This month is named after Julius Caesar. It was Marc Antony who named the month in honor of Julius Caesar, because it was the month Caesar was born in. It used to be called Quintillis (5th) and August was Sextillis (6th), as these months would have been the fifth and sixth months in the Roman lunar calendar. By the way, until around 1800 July was pronounced "julie."
August - Now you see why the Romans took one day from February to make July and August equal. For August is named after Caesar Augustus. Augustus means "majestic" as well as "venerable" in Latin.
September - September is from the Latin word for seven, septem.
October - October is from the Latin for eight, octem, derived from the hellenic one οκτώ.
November - November is from the Latin word for nine, novem.
December - December is from the Latin for ten, decem, derived from the hellenic one δέκα.
Excerpts from The Facts on File Encyclopedia of Words and Phrase Origins. Checkmark Books: New York 2000 by Hendrickson, Robert & Commentary - Editing by Irene Doura-Kavadia