A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Date systems - Month, day, and year
Numbers
Part III. Style 20 spelling

Presenting dates in text involves many of the same concerns as in 23.1 and 23.2 but also some conventions for ordering and naming elements.

23.3.1 Month, day, and year

Spell out the names of months when they occur in text, whether alone or in dates. Express days and years in numerals, and avoid using them at the beginning of a sentence, where they would have to be spelled out (see 23.1.2). Do not abbreviate references to the year (“the great flood of '05”). For abbreviations acceptable in tables, figures, and citations, see 24.4.2.

Every September, we recall the events of 2001.

but not

Two thousand one was a memorable year.

For full references to dates, give the month, the day (followed by a comma), and the year, in accordance with U.S. practices. If you omit the day, omit the comma. Also omit the comma for dates given with seasons instead of months; do not capitalize the names of seasons (see 22.1.2). If material you are quoting uses British-style dates (15 March 2007), do not alter them.

President John F. Kennedy was assassinated on November 22, 1963.

By March 1865, the war was nearly over.

The research was conducted over several weeks in spring 2006.

Note that, within complete dates, days are generally not given as ordinals—that is, the numerals are not followed by st, nd, rd, or th. Use these endings only with spelled-out numbers when you specify the day without the month or year.

The date chosen for the raid was the twenty-ninth.

but not

The events occurred on June 11th, 1968.