Check out this month’s calendar (February 2015).  It has one of the rarest configurations you will see. There are exactly four weeks, no spilling over to a fifth week.  This only happens in non-leap years when February 1 is on a Sunday; most Februaries are like most other months; they take up five week lines.   The next occurrence of only-four-weeks will be in 2026.

The only rarer calendar look is a leap year February.  29 days; the 1^st and the 29^th are on the same day of the week.  The starting day of the week for leap year Februarys rotates once every 28 years.  February 1 2016 is on a Monday; it will also be on Monday in 2044.  Get ready!

A more common but still unusual month look requires six lines for the weeks.  See August 2015.  Many calendars get all lazy and double up Sunday and maybe Monday and Tuesday when this occurs.  The good honest calendar in the picture gives the six lines we deserve!