Happy Friday the 13th: It’s the 1st of 2 in 2024

Friday the 13th occurs twice in 2024

Today is September 13, 2024, and it’s a Friday. And it’s the first of two Friday the 13ths in 2024. The next one in December. Does that mean 2024 is super unlucky? No. Any calendar year has at least one – but no more than three – Friday the 13ths. The last time we had only one Friday the 13th in a calendar year was in 2022. And the next time won’t be until 2025. Are you scared of Friday the 13th? Or has it just got a bad rap? It’s really just a feature of our Gregorian calendar, and a pretty common one at that.

We last had three Friday the 13ths in 2015, in February, March and November. We’ll have three again in 2026.

There’s a name for having an irrational fear of Friday the 13th: friggatriskaidekaphobia. Not that we at EarthSky suffer from this fear … but, gosh darn, last year’s first Friday the 13th was on January 13, 2023, and it happened exactly 39 weeks (3 x 13 weeks) before the second Friday the 13th in October 2023. And that’s not the end of it.

This year, in 2024, the first of the two Friday the 13th comes on September 13, 2024, exactly 13 weeks before the second Friday the 13th in December 2024. Then the sole Friday the 13th of 2025 falls on June 13, 2025, exactly 26 weeks (2 x 13 weeks) after the December 2024 Friday the 13th.

Yikes, that’s quite a few of coincidences involving the number 13 … and we could cite many more!

Why do some people fear Friday the 13th?

Are all these 13’s a scary coincidence or is it super unlucky? Neither. It’s just a quirk of our calendar, as you’ll see as you keep reading.

The fact is that, according to folklorists, there’s no written evidence that Friday the 13th was considered unlucky before the 19th century. The earliest known documented reference in English appears to be in Henry Sutherland Edwards’ 1869 biography of the composer Gioacchino Rossini, who died on a Friday the 13th.

Unlucky? I don't think so. The 13th is more likely to be a Friday than any other day of the week! https://t.co/aKfOawx8w7 pic.twitter.com/Che7xmZJrv

— Nick Berry (@DataGenetics) October 13, 2017

Has Friday the 13th got a bad rap?

Friday has always gotten a bad rap regardless of its number in the month. Even in the Middle Ages, people would not marry – or set out on a journey – on a Friday.

There are also some links between Christianity and an ill association with either Fridays or the number 13. Jesus was said to be crucified on a Friday. Seating 13 people at a table would supposedly bring bad luck because Judas Iscariot, the disciple who betrayed Jesus, was the 13th guest at the Last Supper. Meanwhile, our word for Friday comes from Frigga, an ancient Norse goddess of marriage and fertility. Christians called Frigga a witch and Friday the witches’ Sabbath.

In modern times, the slasher-movie franchise Friday the 13th has helped keep friggatriskaidekaphobia alive.

In 2024, blame a leap year starting on Monday.

As you know, 2024 is a leap year. And in any leap year of 366 days that begins on a Monday, there are Friday the 13ths in September and December. The next September-December Friday the 13th leap year will take place in 2052.

In the 21st century (2001 to 2100), the first September-December Friday the 13th leap year of 366 days occurs in 2024. This September-December Friday the 13th leap year recurs in cycles of 28 years:

2024 + 28 = 2052

2052 + 28 = 2080

So we find a total of three September-December Friday the 13th leap years in the 21st century (2001 to 2100): 2024, 2052 and 2080.

What about a common year?

We had two Friday the 13ths in 2019 – in September and December – because 2019 was a common year (not a leap year) that started on a Tuesday. Whenever a common year of 365 days starts on a Tuesday, it’s inevitable that the months of September and December will start on a Sunday. And any month starting on a Sunday will have a Friday the 13th.

The next time will be 6 years from now, in 2030.

How often do September-December Friday the 13ths happen? More often than you might imagine! We continue the cycle onward to find a grand total of 11 September-December Friday the 13th 365-day common years for the 21st century (2001 to 2100):

2002, 2013, 2019, 2030, 2041, 2047, 2058, 2069, 2075, 2086 and 2097

Rhyme and reason for the 400-year Friday the 13th cycle.

Because the Gregorian calendar has a 400-year cycle, these twofold September-December Friday the 13th years recur in cycles of 400 years. For example, respective September-December Friday the 13th calendar years are exactly 400 years apart in the 21st and 25th centuries:

21st century (2001 to 2100):

2002, 2013, 2019, 2024 (leap year), 2030, 2041, 2047, 2052 (leap year), 2058, 2069, 2075, 2080 (leap year), 2086 and 2097

25th century (2401 to 2500):

2402, 2413, 2419, 2424 (leap year), 2430, 2441, 2447, 2452 (leap year), 2458, 2469, 2475, 2480 (leap year), 2486 and 2497

How about in other centuries? If you’re up for doing the computations:

22nd century (2101 to 2200): the first common year September-December Friday the 13th happens in 2109, and repeats in cycles of 6, 17 and 28 years. The first leap year September-December Friday the 13th happens in 2120 and recurs every 28 years.

23rd century (2201 to 2300): the first common September-December Friday the 13th year happens in 2205, and repeats every 6, 17 and 28 years. The first leap year September-December Friday the 13th happens in 2216 – but, by Gregorian calendar rules, the year 2300 is not a leap year.

24th century (2301 to 2400): the first common September-December Friday the 13th year happens in 2301, with the days and dates matching up again in periods of 6, 17 and 28 years. The first leap year September-December Friday the 13th happens in 2216.

Read more: A year with 13 Friday the 13ths?

As magical as all of this Friday the 13th calendar intrigue appears to be, it’s not supernatural. It’s entertaining number play, even if it may haunt our uncomprehending minds.

Friday the 13th, by the numbers | @DataGenetics https://t.co/ET7kqCAqY4
Image via: https://t.co/5GcrRV6nC9 pic.twitter.com/r3IuwSmnkz

— VMware Tanzu Data (@VMWareTanzuData) November 13, 2015

Bottom line: Scared of Friday the 13th? It’s just a feature of our Gregorian calendar, and a pretty common one at that. And from what we’ve been able to gather, the 400-year cycle displayed by the Gregorian calendar features 688 Friday the 13ths.

When does Friday the 13th have a full moon?

The post Happy Friday the 13th: It’s the 1st of 2 in 2024 first appeared on EarthSky.