Here is a historical analysis of the crypto market for the month of September, its recurring trends, the exceptions, and what this could mean for the future.
History & trends
The “Redtember”
Traditionally, the month of September is considered one of the weakest months for Bitcoin (and often for the crypto market in general). Since 2013, Bitcoin has averaged a decline of 3% to 5% during September.
In “Redtember”, investors observe an increase in volatility, withdrawals or profit-taking, and sometimes negative regulatory announcements that weigh on sentiment.
Frequency of negative performances
Over the last 12 years, September has been a negative month for Bitcoin in a high proportion of cases. For example, in 10 of the last 15 years, September has ended down.
This is not an absolute rule — there have been notable exceptions recently.Exceptions & possible reversals
September 2024 was a strong exception, with a net gain of around 7–8%, making it exceptionally good for this month.
In 2025 as well, Bitcoin seems to defy this negative seasonal trend: the month is on a path of positive performance, one of the best for September in a long time.
Explanatory factors for these trends
Regulation & macroeconomic announcements
Many of the negative September months coincided with significant regulatory announcements (e.g. restrictions, bans, high inflation) or political uncertainties. These events fuel nervousness and trigger capital outflows.
Seasonal effect & investor psychology
After summer — often a calm period, with lower volumes — investors may induce a correction or profit-taking in September. Activity resumes, but often with caution.Pullback before Q4 rally (October & Q4)
Historically, the months following September (notably October and November) have often been the most favorable for the crypto market. The fourth quarter frequently generates strong gains, often after the lows of September.
What 2025 shows that is new
Challenge to past seasons
In 2025, Bitcoin seems to break the usual pattern: September is positive, driven by institutional flows, Bitcoin ETFs, and favorable expectations regarding rates or monetary policies.
Lower volatility despite bullish market context
Contrary to what one might expect in a strong rising or disruptive period, volatility seems moderate so far, indicating maturity or more thoughtful behavior from the market.
Attention to confirmed signals
Even if historical trends have often predicted declines, exceptional years remind us not to rely solely on seasonality. The combination of factors such as the influx of institutional money, macroeconomic policies, or the regulatory context could reverse or limit the decline.
Cautious positioning before the end of the month
If technical supports hold and announcements are not negatively sourced, the market may continue to consolidate, even pushing upwards towards Q4. However, corrections or partial pullbacks remain plausible given the 'end of summer caution.'Looking towards 'October'
If September serves as a low point or consolidation, October and November could offer stronger upward opportunities. Medium-term traders and long-term investors could benefit by observing the support levels established during September to decide their positions.Diversification & risk management
Using stop-losses, reducing leverage, maintaining liquidity, and diversifying between crypto and more stable assets remain relevant strategies, especially in a context where seasonality could play against the market.