What Is Bitcoin's Worst Month? The Data Says August
Ask most people which month is worst for Bitcoin and they will say September. September has the reputation, the memes, and the warning posts that resurface every single year. The data points somewhere else.
Ranking all twelve months
The fair way to compare months is not the average. Bitcoin's averages are distorted by a handful of enormous outlier months, and a single freak year can drag a whole month's average into positive territory. The honest measure is the typical year, the middle outcome when you line every instance of that month up in order.
Ranked that way, from 2010 through 2025, this is what Bitcoin's calendar looks like:
- October +13.0%, February +11.8%, April +10.0%
- November +8.5%, July +8.4%, May +6.9%
- January +5.2%, December +2.2%, June +2.0%
- March -0.9%, September -2.4%
- August -8.6%
Nine of the twelve months are positive in a typical year. Three are negative. And one of those three is not close to the others.
August is nearly four times worse than September
September, the month with all the warnings attached to it, has a typical year of -2.4%. Uncomfortable, but survivable, and well within the range of an ordinary month.
August's typical year is -8.6%. That is the worst reading on the entire calendar, and it is roughly 3.6 times worse than September. It is also the only month that loses more than three percent in a typical year.
The reputation and the record do not match.
It is not one bad year dragging the number
A single ugly outlier can make any month look terrible, so the consistency matters more than the size.
Since 2010, August has finished green only 5 times out of 16. Eleven of the last sixteen Augusts lost money. That is roughly a two in three chance of a red month before you consider anything else about the market at all.
The average tells a different story, and this is worth understanding. August's average is -1.8%, which is much gentler than the -8.6% typical year. The gap exists because 2017 rose 65.6% in August, almost single-handedly lifting the average while leaving the typical outcome untouched. When an average and a middle outcome disagree this sharply, the middle is the one describing what usually happens to you.
The month is not the cause
None of this means the calendar has power over price. August does not reach out and sell Bitcoin. What actually varies is the condition Bitcoin walks into the month carrying.
Split the record by that and the pattern sharpens considerably. In the four genuine bear markets Bitcoin has had, the ones that followed the 2011, 2013, 2017 and 2021 cycle tops, August finished red every single time:
- 2011: -38.7%
- 2014: -17.8%
- 2018: -9.1%
- 2022: -14.3%
Four bear markets, four red Augusts, no exceptions.
There is a second mechanism underneath the seasonality too, and it is not mystical. Trading volume through June, July, August and September runs roughly 13% lighter than an average day of the year. Those four are the quietest months on the calendar. Thinner markets have fewer buyers standing ready to absorb selling, so the same size of sell order pushes price further than it would in a busy month. Summer does not create bad news. It makes whatever news arrives travel further.
Where Bitcoin sits going into this one
As of the July 30 close, Bitcoin is trading around $64,700, roughly 10% below its 200-day average, which is the simplest marker of its long-run trend. That places it on the weaker side of the split above.
Measured from the end of May on the same basis used throughout this piece, Bitcoin is down about 12% on the summer already, with two months of it still to run.
So the month with the worst record on Bitcoin's calendar begins tomorrow, and Bitcoin walks into it from the wrong side of its trend, already down double digits for the season.
What this is and is not
This is a lean in the odds, not a forecast. Sixteen Augusts is sixteen data points, and four bear markets is four. Seasonality describes what has usually happened, and it has been wrong before. August 2017 gained 65.6% while Bitcoin sat well below its previous high, which is exactly the kind of exception that stops any of this from being a rule.
What it is useful for is expectation setting. If you are positioned as though August is an ordinary month, the record says you are positioned for the wrong month. Planning for a grind and being pleasantly surprised is a better place to stand than planning for a recovery and being caught by the most reliably negative month on the calendar.
We put the full breakdown into a free guide, including what August and September have historically done from a drawdown like this one and the single price level worth watching. You can read the Summer Playbook here.
Education, not financial advice.
Common questions
What is Bitcoin's worst month?
August. Ranked by the typical year from 2010 to 2025, August returns -8.6%, the worst of any month on the calendar and nearly four times worse than September at -2.4%. August has been green only 5 times in 16 years.
Is September really bad for Bitcoin?
It is mildly negative, not brutal. September's typical year is -2.4%, which is worse than most months but far milder than its reputation suggests and far milder than August.
Why does Bitcoin fall in August and September?
The calendar is not the cause. Volume across June to September runs about 13% lighter than an average day, so fewer buyers are available to absorb selling and the same sell order moves price further. The condition Bitcoin enters the month in matters far more than the month itself.
Has August ever been positive for Bitcoin?
Yes, five times since 2010. August 2017 gained 65.6%, 2013 gained 31.0%, and 2021, 2012 and 2020 were also positive. But in the four genuine bear markets, 2011, 2014, 2018 and 2022, August finished red every time.
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Education, not financial advice. Trading involves real risk.