Bitcoin in September: historically weakest month begins

September is traditionally the weakest month for Bitcoin. Historical data from Coinglass shows that the average monthly price movement in September comes out at -3.08%, with a median of -3.12%. Nevertheless, analyst DaanCrypto warns that seasonal patterns do not always hold. August performed surprisingly strongly this year with a gain of 24.04%, even though that month has historically also been lacklustre.

Bitcoin is available at OKX and Bybit.

In brief:

• September is historically Bitcoin’s worst month, with an average loss of 3.08%
• August 2026, by contrast, ended strongly with a gain of more than 24%
• Analyst DaanCrypto expects sidelined capital to play a decisive role this month

Historical pattern points to a difficult month

The Coinglass data on monthly Bitcoin returns dates back to 2013. During that period, September closed in negative territory almost every year. Only in 2023 (+3.91%) and 2015 (+2.35%) was there a small gain. The remaining years produced losses ranging from -1.76% in 2013 to -13.38% in 2019.

October appears predominantly green in the historical overview, with an average return of +19.92%. That makes the fourth quarter the most attractive entry point of the year for many investors.

Sidelined capital can make the difference

DaanCrypto states that many investors have deliberately waited to enter the market because of the historically weak August and September. Now that September has begun, the question arises whether that held-back capital will still flow into the market or will wait for a further dip towards October.

The analyst indicates that he himself is not waiting for a specific price level or point in time. When Bitcoin dropped below $70.000 in January, he opted for a staggered buying strategy. At the moment, the Bitcoin price is hovering around $78.600, an increase of 0.5% over the past 24 hours.

Whether the seasonal pattern will apply again this year remains uncertain. As the strong August already showed, significant inflows via Bitcoin ETFs and other factors can easily break historical trends. The decision investors make this month about their position will largely determine how September turns out for Bitcoin.