From Houghtaling's Handbook of Useful Information ©1887
January - The Roman Janus presided over the beginning of everything; hence the first month of the year was called after him.
February - The Roman festival Februs was held on the 15th day of this month, in honor of Lupercus, the god of fertility.
March - Names from the Roman god of war, Mars.
April - Latin Aprillis, probably derived from asperire, to open; because spring generally begins and the buds open in this month.
May - Latin Maius, probably derived from Maia, a feminine divinity worshiped at Rome on the first day of this month.
June - Juno, a Roman divinity worshiped as the Queen of Heaven.
July - (Julius). - Julius Caesar was born in this month.
August - Named by the Emperor Augustus Caesar, B.C.30, after himself, as he regarded it a lucky month, being that in which he had gained several victories.
September (septem, or 7) - Septemeber was the seventh month in the old Roman calendar.
October (octo) - Eighth month of the old Roman year.
November (novem, or 9) - November was the ninth month in the old Roman calendar
December (decem, or 10) December was the tenth month of the early Roman year. About the 21st of this month the sun-enters the Tropic of Capricorn, and forms the winter solstice.