Why Do We Have 12 Months Instead of 13?
Why are there 12 months in the year? Julius Caesar's astronomers explained the need for 12 months in a year and the addition of a leap year to synchronize with the seasons. At the time, there were only ten months in the calendar, while there are just over 12 lunar cycles in a year.

Should there be 13 months in a year?

The calendar year has 13 months with 28 days each, divided into exactly 4 weeks (13 × 28 = 364). An extra day added as a holiday at the end of the year (after December 28, i.e. equal December 31 Gregorian), sometimes called "Year Day", does not belong to any week and brings the total to 365 days.

What was the 13 month called?

Undecimber or Undecember is a name for a thirteenth month in a calendar that normally has twelve months. Duodecimber or Duodecember is similarly a fourteenth month.
James H. Sterling

James H. Sterling

Environmental Science & Climate Journalist

James Sterling reports on renewable energy developments, climate policy, ecological conservation, and green tech innovations around the globe.

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