Comparable sales rose 11.6% in the four weeks to 3 May, while US core comparable sales increased 8% and warehouse traffic accelerated to 4.2%.
The retailer said customers kept seeking value and cheaper fuel, with higher petrol prices and an Easter timing shift that added an extra shopping day helping results.
Investors are now focused on membership renewal rates ahead of Costco's 28 May quarterly report; shares edged above $1,000 and are up about 16% this year.
Costco's sales are soaring but memberships are slipping. Is its core profit engine starting to sputter?
With the Hormuz crisis raising costs, can Costco protect shoppers from inflation beyond the gas pump?
Is Costco's sales boom a sign of strength or a dangerous reliance on the ongoing Iran war?