Costco (COST) Seasonality
Recurring seasonal patterns for COST — the calendar windows where Costco has historically tended to rise or fall, with the win rate (how often it repeated) and average return for each, based on the last 10 years of price history.
COST seasonality at a glance
Over the last 10 years, COST's strongest seasonal window has been Oct 31 – Nov 30: it ended higher in 10 of 10 years (100% win rate) with an average return of +6.48% across a 30-day hold. On the weak side, COST has historically declined between Sep 18 – Oct 8, falling in 9 of 10 years (average -1.38%).
In total, our analysis finds 694 recurring seasonal windows for Costco — 579 bullish and 115 bearish. The next high-win-rate window, Sep 18 – Oct 8, opens in 7 days. These figures describe historical behaviour only — not a forecast.
COST's upcoming & recent seasonal patterns
Holding period:10-day20-day30-dayOrdered by season — windows opening soon first, plus a couple of recently completed high-performers. Holding-period colors help you compare durations at a glance.
| Status | Seasonal window | Hold | Avg return | Win rate | This year |
|---|---|---|---|---|---|
| Completedended 19d ago | Jul 24 – Aug 23 | 30d | +2.95% | 80% | +1.36% |
| Completedended 20d ago | Jul 23 – Aug 22 | 30d | +3.03% | 80% | +2.50% |
| Upcomingin 7d | Sep 18 – Oct 8 | 20d | -1.38% | 90% | — |
| Upcomingin 24d | Oct 5 – Oct 25 | 20d | +2.04% | 80% | — |
| Upcomingin 25d | Oct 6 – Oct 16 | 10d | +1.42% | 90% | — |
| Upcomingin 25d | Oct 6 – Oct 26 | 20d | +2.23% | 80% | — |
| Upcomingin 25d | Oct 6 – Nov 5 | 30d | +3.89% | 90% | — |
Win rate = how often the pattern repeated in the same direction. Average return = the mean move across all analysed years. Past performance does not guarantee future results.
Explore COST seasonality in full
See the seasonal curve chart, filter by win rate and return, and track upcoming windows — free during beta.
COST seasonality FAQ
What has historically been the best month to buy COST stock?
Based on the last 10 years of price data, COST's strongest seasonal window starts in October: Oct 31 to Nov 30, which ended higher in 10 of 10 years (100% win rate) with an average return of +6.48%. Past seasonal patterns do not guarantee future performance.
What is COST's strongest seasonal pattern?
COST's highest-win-rate pattern in our data is the Oct 31 – Nov 30 window (30-day hold): up in 10 of the last 10 years with an average move of +6.48%.
When has COST historically performed worst?
COST's weakest recurring window has been Sep 18 to Oct 8, declining in 9 of 10 years with an average return of -1.38%.
How reliable are COST's seasonal patterns?
Each COST pattern is scored by its historical win rate — the share of the last 10 years it repeated in the same direction. COST currently shows 694 recurring windows (579 bullish, 115 bearish). Seasonality describes historical tendencies only; it is not a prediction, and past performance does not guarantee future results.
What is COST stock seasonality?
Seasonality is the tendency of a stock to perform in a similar way during the same period each year. By analysing Costco's price history across many years, SeasonalityX identifies recurring calendar windows — exact start and end dates — where COST has repeatedly risen (bullish) or fallen (bearish). Each pattern is scored by its win rate and average return so you can judge how reliable and how strong it has been.
Seasonality is one input among many — it works best alongside your own research and risk management. Learn more in our guide to seasonal analysis and the tutorials.