Costco Hours: Memorial Day 2018 by Rhonda July 16, 2020 5/28/18. Costco will be closed on Monday, May 28, 2018, in observance of Memorial Day. 0 FacebookTwitterPinterestEmail previous post Costco Sale: Bestway H20Go! Family Pool with Slide $29.99 next post Costco Sale: GoPro HERO5 Black Action Camera Bundle You may also like Midea 3.3 Cu. Ft. Compact Refrigerator – Costco... Universal Broadmoore Anna 72″ Accent Console at Costco! Plush Step Area Rug 7’10” x 10′ –... Costco Unadvertised Sales! FEBRUARY 2023 Kirkland Signature Tempura Shrimp – Costco Sale! Costco Coupon Book FEBRUARY 2023