Q. Is it true that every 3 years the Jews would add a 13th month to their calendar? So,in a 7 year cycle of time 60 days would be added somehow. I’m not coming against the 2520 days written Biblically. I know those are literal and mean what they say. In other words,in a 7 year period,will a 13th month be added twice in that span of time?
A. The Hebrew calendar is based on lunar cycles and a normal year is only 354 days long, about 11 days shorter than a year on our western solar calendar. When they get to be about one month behind they add a 13th month to “catch up” with the solar year. This happens every 2 or 3 years on a predetermined schedule. But remember, this is done to keep the Hebrew calendar current with ours. So while the number of months may vary, over time the number of days averages out to be the same.