September Is Bitcoin’s Worst Month But BTC Is Up 7.8% So Far. What Does This Mean for Q4?

September is historically Bitcoin’s worst month, yet this year it has defied expectations with a 7.8% increase so far. After a remarkable 25% gain in August, many are wondering what this trend could mean for the fourth quarter.

Looking at past data from CoinGlass, Bitcoin (CRYPTO:BTC) has lost value in eight out of the 13 Septembers since 2013, with an average loss of about 2.9%. This month, however, has taken a different turn. Bitcoin ended August at $78,563 and is trading at $84,702 as of September 21, 2026—a rise of 8.2% for the week, 7.8% this month, and 10% over the past 30 days.

This impressive rise occurred despite setbacks. Bitcoin dropped to around $76,000 after the Senate halted the CLARITY Act on September 15 and the Federal Reserve raised interest rates on September 16. Nevertheless, it rebounded sharply, surging 11% over the next five days. So what does a positive September suggest about Q4?

September’s Bad Reputation Comes from One Five-Year Streak

While September’s average return is quite low, it largely stems from a rough five-year period from 2017 to 2021, when Bitcoin consistently lost value during this month. Those years came before spot ETFs and corporate treasury buying, which are now key factors in the market.

The trend has changed in recent years. Bitcoin gained 3.9% in September 2023, 7.3% in September 2024, and 5.2% in September 2025. A trader betting against Bitcoin in September over the past three years would have faced losses, breaking the pattern of expecting a downturn.

This September is on track to become the fourth consecutive green September. It follows a strong August—the best month of 2026—and a solid 7.4% gain in July, showing that momentum has carried into this month.

A Green September Has Led to Strong Fourth Quarters for Bitcoin

Traders are watching September closely because a green month typically leads to a strong fourth quarter. In years where Bitcoin closed higher in September—specifically 2015, 2016, 2023, and 2024—the subsequent fourth quarters also saw gains, with increases of 57% in 2023 and 48% in 2024, according to CoinGlass. This trend is what has earned October the nickname “Uptober,” as it is Bitcoin’s strongest month.

However, the pattern broke most recently in 2025, when September ended with a 5.2% gain, but Q4 fell sharply by 23.1%. The drop began on October 10, when a tariff threat from President Trump triggered about $19 billion in liquidations, and the price never recovered that ground before December 31. A seasonal average cannot see a shock like that coming.

Bitcoin Heads into Q4 Strong, but with Challenges Ahead

Heading into the fourth quarter, Bitcoin is up 45% since the end of Q2 but still down about 3% from its December 31, 2025, closing price of $87,498. Two main factors will determine if it can close this gap.

First, spot Bitcoin ETF performance will be crucial. These funds helped fuel the 2024 rally but managed to bring in just $6 million in the week to September 18, after a $463 million outflow the week before. For Q4 to mirror the strong growth seen in 2023 or 2024, consistent buying from these funds will need to occur throughout October.

Second, maintaining a Bitcoin price above $78,563 as we move into October is vital. Staying above this level keeps the momentum from July intact. If Bitcoin slips below this mark, a negative October trend could re-emerge.

So while a positive September suggests an upward trend heading into Q4, the quarter itself will depend on ETF activity and Bitcoin’s ability to hold that level.

What Does a Green September Indicate for the Fourth Quarter?

It suggests that the trend moving into October is positive. Historically, four out of the last five times this happened led to gains. Bitcoin’s price is currently 7.8% higher than where it ended in August, despite September typically averaging a 2.9% loss. The three previous Septembers were also green, meaning the “worst month” label now applies to a Bitcoin market that hasn’t existed since 2021. The green Septembers in 2023 and 2024 resulted in fourth-quarter gains of 57% and 48%, respectively.

However, the 2025 scenario shows a downside; it had a similar setup but experienced a 23.1% loss that quarter after one bad day. So, while a green September is promising, it doesn’t guarantee protection against another downturn like on October 10. The fourth quarter now hinges on whether ETFs will keep buying and if Bitcoin can hold above $78,563. If both conditions hold through October, the green September could signal the start of a strong quarter. But if one breaks, we may see a return to those challenging October trends, with Bitcoin chasing a price of $87,498 by year-end.

Contact [email protected] for any questions or corrections.