God’s Lunisolar Calendar
The phrase "God's lunar calendar" refers to the Hebrew (Jewish) calendar, which many people describe as God's calendar because it's the one used in the Bible for festivals, new moons, and religious observances. It's called a lunisolar calendar — it follows the moon for months but stays roughly aligned with the sun (seasons) for years.
Why it sometimes has 12 months and sometimes 13. A purely lunar calendar (based only on moon cycles) has months that start with each new moon. Each lunar month is about 29.5 days long, so 12 lunar months add up to roughly 354 days.
But a full solar year — the time it takes Earth to orbit the sun, which controls our seasons — is about 365.25 days. That's around 11 days longer than 12 lunar months.
If you just used 12 months every year, the calendar would drift backward by about 11 days each year compared to the seasons. After a few years, spring festivals (like Passover, which the Bible says must be in spring) would end up happening in winter, summer festivals in spring, etc. — which wouldn't make sense for an agricultural/seasonal people.
To fix this and keep the calendar in sync with the seasons, an extra month is added from time to time. This makes some years have 13 months instead of 12. The extra month (always a second Adar, called Adar I and Adar II) pushes the calendar forward to catch up.
How often does a 13-month year happen?
The modern Hebrew calendar uses a very accurate repeating pattern discovered in ancient times (related to the Metonic cycle):
• Over every 19 years, there are 7 years with 13 months (leap years) and 12 years with 12 months (common years).
• This adds up almost perfectly: 19 solar years ≈ 235 lunar months (12 × 19 = 228 months + 7 extra = 235).
The 7 leap years in the 19-year cycle occur in specific positions (years 3, 6, 8, 11, 14, 17, and 19 of the cycle). So roughly every 2–3 years on average, there's a 13-month year, but not strictly every 2 or 3 — it follows the fixed pattern.
In simple terms:
The moon gives short years (354 days), but seasons need longer ones (365 days). Adding an extra month 7 times every 19 years keeps God's calendar beautifully balanced between moon phases and solar seasons, so holidays always fall in the right time of year.
2026
Search for related topics. * United Church Of God - UCG - ucg.org