FromJulyof the year that precedes this type of year untilSeptemberin this type of year is the longest period (14 months) that occurs without aFriday the 17th.Leap years starting on Tuesdayshare this characteristic, fromAugustof thecommon year that precedes ittoOctoberin that type of year, (e.g. 2007-08 and 2035-36). This type of year also has the longest period (also 14 months) without aTuesday the 13th,from July of this year until September of the next common year (that being onSaturday), unless the next year is a leap year (which is also aSaturday), then the period is reduced to only 11 months (e.g. 1999-2000 and 2027-28).
This is the one of two types of years overall where arectangular Februaryis possible, in places where Monday is considered to be the first day of the week.Common years starting on Thursdayshare this characteristic, but only in places where Sunday is considered to be the first day of the week.
Additionally, this type of year has three months (February, March and November) beginning exactly on the first day of the week, in areas which Monday is considered the first day of the week.Leap years starting on Mondayshare this characteristic on the months of January, April and July.
In the (currently used) Gregorian calendar, alongsideSunday,Monday,WednesdayorSaturday,the fourteen types of year (seven common, seven leap) repeat in a 400-year cycle (20871 weeks). Forty-three common years per cycle or exactly 10.75% start on a Friday. The 28-year sub-cycle only spans across century years divisible by 400, e.g. 1600, 2000, and 2400.
For this kind of year, the ISO week 10 (which begins March 8) and all subsequent ISO weeks occur later than in all other years, and exactly one week later thanLeap years starting on Thursday.Also, the ISO weeks in January and February occur later than all other common years, butleap years starting on Fridayshare this characteristic in January and February, until ISO week 8.
In the now-obsolete Julian calendar, the fourteen types of year (seven common, seven leap) repeat in a28-year cycle(1461 weeks). This sequence occurs exactly once within a cycle, and every common letter thrice.
As the Julian calendar repeats after 28 years that means it will also repeat after 700 years, i.e. 25 cycles. The year's position in the cycle is given by the formula ((year + 8) mod 28) + 1). Years 4, 15 and 26 of the cycle are common years beginning on Friday. 2017 is year 10 of the cycle. Approximately 10.71% of all years are common years beginning on Friday.
