Sunday, August 1, 2010

Five Sundays in August 2010 and other finds in the birthday month

First of August Sunday morning blog.

My mother read to me an SMS message the other day which said something about August 2010 as having "...5 Sundays, 5 Mondays and 5 Tuesdays" and that "this won't happen again in another 823 years".

I checked the wall calendar and fired up my calendar in the Dashboard, scrolled through all the months of 2010 out of curiosity and found out three other 5-day combinations-in-a-month. These are:

  • May 2010 with 5 Saturdays, 5 Sundays and 5 Mondays
  • July 2010 with 5 Thursdays, 5 Fridays and 5 Saturdays, and
  • December with 5 Wednesdays, 5 Thursdays and 5 Fridays
So I guess August and May 2010 are special to others because it has 5 Sundays, Sunday being a sacred day to most Christians as it is a "day of obligation," meaning, the Christian world takes a rest from all worldly obligations to give of themselves to THAT day of Obligation—to worship, ask for forgiveness and give thanks.

While looking for more information on this supposed phenomenon, I came upon entries about August 2009, which, on the other hand, had 5 Saturdays, 5 Sundays and 5 Mondays just like what May 2010 had (both occurrences escaped my attention).

In 1187, or 823 years ago, the Gregorian calendar hadn't existed yet (it was introduced in 1582) so there was no ado about this strange happenstance.

I haven't come across any other reference about it happening in 823 years interval, but I guess it means the next Sunday-Monday-Tuesday combination in 28331 will be referencing this year's, unless the Gregorian calendar is changed to something else that befits the future. I don't know.

It's something to think about over late-morning breakfast coffee.

1The year should have been 2832 as pointed out by reader Matt in the comments below. Thanks, Matt. 
Image, top: Georges Seurat, A Sunday on La Grande Jatte mug from
Calendar images grabbed from my Dashboard, added 04 August 2010


  1. August 1999, 2010, 2021, 2032 all have 5 Sundays, 5 Mondays and 5 tuesdays.. And I suspect this repeats every 11 years..

  2. Actually: No. If you wait 11 years, AUGUST 2021 has 5 Sundays, 5 Mondays, 5 Tuesdays. All 31 day months have three consecutive days that occur five times. With only seven possible starting points, it happens way more often than every 823 years.

    In fact: it doesn't even happen in 2833, that has five Mondays, Tuesday, Wednesday. Does occur in 2832 though.


  3. August 4, 2010 12:17 PM K1000 said...
    August 1999, 2010, 2021, 2032 all have 5 Sundays, 5 Mondays and 5 tuesdays.. And I suspect this repeats every 11 years..

    Thank you for your comment and for doing the math. I haven't the time to check but your adding another layer of info to this post may hopefully be of use to someone.

    Cheers- :)

  4. August 4, 2010 3:57 PM Matt said...
    ... With only seven possible starting points, it happens way more often than every 823 years.

    In fact: it doesn't even happen in 2833, that has five Mondays, Tuesday, Wednesday. Does occur in 2832 though.

    Thanks, Matt.

    I suspected that the occurrence may indeed happen more often than 823 years, just wasn't sure at the point of posting when the intervals would be.

    Yes, August 2832 it is for 5 Sun-Mon-Tue days (thanks for pointing that out) and *not* 2833
    which, on the other hand, will have 5 Mon-Tue-Wed days.

    ~ K

  5. there is absolutely NOTHING "astounding" or mysterious about having 5 Sundays/Mondays/Tuesdays in august this year.

    EVERY single month with 31 days gets a sequence of three consecutive days repeated five times. It can't be ANY other way.

    In other words, this happens 7 times a year, since there are 7 months with 31 days.

    How could anyone believe that this happens only once every 800 years? This all stared because a person on Twitter wanted to start a "mystical rumor". And it's all bull.

    Before posting this sort of thing on a blog you should be more skeptical!

  6. Hey Mikey,

    Thanks for your comment.

    I don't think I was at all astounded or mystified by the interval, especially since there are other months in 2010 alone that have it.

    I did notice that the topic has come up on Tweets in the past few days (and in Google searches, for instance, as I see that many have landed on this blog from it), something which—I must admit—was more of a surprise to me than anything.

    The first time I came upon this August fact (as I've written above) was from a local SMS that has obviously done the rounds.

    Guess you have to read the post again to see that it's there simply because my attention was called to it and August happens to be my birthday month.

    Consider it one of those trivial things that litter the interweb or something that may come up in parlor games. Again, I said someone might just find this whole thing useful. Who knows?


  7. I heard this rare calendar occurrence on NPR this morning. But you completely debunked the claim of only happening 800+ years ago! At least someone is researching the numbers....

  8. autumn tome,

    Thanks for commenting and finding the post useful.

    I love your blog's theme and design, by the way. Fun to read, too.


  9. hey, i came here via a google search because i too had got a similar sms from one of my friends. But some cricinfo fan had already pointed out the fallacy in the same comment posted by some other cricinfo fan regarding this rumor.

    Thankfully, matt's comments clarified my doubts.

  10. You don't need any math to figure this out. It happens every time that August starts on a Sunday. And that, of course, happens once every seven years, on average.

  11. It actually happens every 6, 11, 6, 5 years (if I didn't miss any year, feel free to correct this)....

    August 1976, 1982, 1993, 1999, 2004, 2010, 2021, 2027, 2032 all have 5 Sundays, 5 Mondays, and 5 Tuesdays.

  12. In fact if it's not August specific the next occurence then it next happens in May 2011

  13. In my 48 years it has happened 7 times: 2004, 1999, 1993, 1982, 1976, 1971, and 1965. The next time will be 2021.

    As Dan Korn said, it happens on average every 7 years, as there are are only 7 days in a week that August 1 can fall upon. But since we have been observing leap year, it never occurs in a 7 year cycle. Because of leap year every 4th year, it occurs every 5-6 or 11-12 years - depending on how many leap years there are between occurences, and when it happens that leap year kicks August 1 from a Saturday to a Monday (instead of from Saturday to Sunday in a normal year of 365 days).

  14. This normally happens every 5 to 7 years... it happened in 2004, 1999, 1993... the only thing that impacts the consistency is how many leap years occur between each one, and that causes a 1 or 2 year variance each time, except when a leap year occurs on the year that August is supposed to otherwise have its first day on a Sunday, in which case it may skip ahead and take another 5 years to come back around. August 2016 should have the 1st be a Sunday, but because it's a leap year that year, it skips to Monday, and then takes 5 years to come back around again, in 2021.


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