Bitcoin posts an Unprecedented August in a Bear market, but September Already Threatens The Rally

Bitcoin has just closed August up approximately 24.6%, its best month since November 2024 and its strongest August since 2017. Even more unusual, BTC delivered this performance while remaining nearly 38% below its October 2025 all-time high. If the classic definition of a bear market—a decline of more than 20%—is used, this is a first.

The problem? In Bitcoin’s history, a positive August has almost always been followed by a much less pleasant September.

Bitcoin has just broken a statistical first

August’s move is already spectacular. Bitcoin was still close to 63,000 dollars at the start of the month before rising above 81,000 dollars and closing around 78,000 dollars.

We had already detailed Bitcoin’s best August since 2017. The final close now confirms the reversal: approximately +24.6% in August, even though BTC remains down for the whole of 2026.

That last point is what makes the move unusual. The previous major positive Augusts—in 2013, 2017, 2020 and 2021—occurred in markets that were already much more favorable.

In 2026, Bitcoin is still recovering from a bear market that saw it lose nearly 50% from its peak. Reuters had already noted the return above 80,000 dollars, driven in particular by dollar weakness and the return of the “debasement trade.”

A positive August has always punished September

On the historical series generally used by traders, four Augusts since 2013 clearly stand out as positive.

August 2013: +30.4%. September: approximately -1.8%.

August 2017: +65.3%. September: -7.4%.

August 2020: +2.8%. September: -7.5%.

August 2021: +13.8%. September: -7%.

Four precedents. Four red Septembers.

Broad seasonality offers little help either. September remains historically one of Bitcoin’s weakest months, with average returns long standing at around -3%.

This time, macroeconomics is adding pressure. As we explained in our calendar of the four events capable of shaking Bitcoin this week, US employment, inflation and the Fed will quickly put the rally to the test.

The market now assigns a probability of more than 60% to a rate hike in September.

What if 2026 also broke this curse?

However, the history is not quite so simple.

Bitcoin has just recorded three positive Septembers in a row: approximately +4% in 2023, +7.4% in 2024 and +5.4% in 2025. The streak shows that the so-called “September curse” has already weakened.

The technical level also matters. Bitcoin needs to reclaim 80,000–82,000 dollars to clearly extend its rebound. Below that zone, profit-taking remains easy to justify after a rise of nearly 25% in one month.

September 15 will bring another key date with the crucial vote on the CLARITY Act in the US Senate.

August 2026 has already broken one statistic: Bitcoin had never before posted such a strong positive month while trading so far below its previous peak. September must now break a second one.

Previous positive Augusts point to red. The last three years point to green. This time, history no longer offers a single answer.