Bitcoin closed September with a 5.16% gain, its third-best September on record since 2013, according to Coinglass data.

The performance comes as traders turn their attention to October, which has historically been the asset’s strongest month.

Since 2013, bitcoin has averaged 14.4% gains in October, with a median return of 10.8%. Out of 13 Octobers in that span, 10 ended in the green and only three closed lower. That track record makes October the most statistically favorable month for the asset, with gains often clustering in the second half.

Such seasonality is a hallmark of financial markets, with markets tending to recede at the beginning of May before a spike in November. This is based on the belief that equity markets underperform during the summer due to lower trading volumes, reduced institutional activity, and historical returns data.

Historically, U.S. stock markets have shown weaker performance from May through October than from November through April, leading to the strategy becoming a seasonal rule-of-thumb for some investors.

Bitcoin also shows recurring seasonal patterns, often influenced by macro cycles, institutional flows, and retail sentiment. As such, past trading patterns show the first week of October can be choppy or negative, before stronger upside takes hold later in the month. In several years, bitcoin posted double-digit surges after Oct. 15, even when early price action was muted.

The backdrop this year is similar. Bitcoin’s mixed performance through 2025 — including drawdowns in spring and uneven summer trading — contrasts with the resilience of recent weeks, adding weight to the idea that September’s strength may be a precursor to late-year momentum.

Still, seasonality offers probabilities, not certainties. Macro catalysts, from U.S. inflation prints to shifts in risk appetite, have historically shaped October’s rallies.

But with September’s performance ranking near the top and the odds favoring bulls in October, traders will be watching closely to see if history rhymes once again.