These figures are computed from 15 years of actual monthly closing prices. Past seasonal patterns are not a guarantee of future performance. See our methodology for how this is calculated, or visit the Academy to learn how to read seasonal data responsibly.
Costco seasonality — common questions
What is Costco's best month historically?
Historically, November has been Costco's strongest month, averaging +5.95% with a 100% win rate over 15 years of data. December has been the weakest at -1.40%.
Is Costco seasonal?
Costco shows a measurable seasonal pattern: its best and worst months differ by 7.35 percentage points on average. These figures come from 15 years of real monthly closing prices. Seasonality is a historical tendency, not a prediction.
How does Costco historically perform in August?
Costco is currently in August, which has historically averaged +1.50% with a 56% win rate. That is a historically neutral window.
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