Excessive heat, stifling humidity and blinding sun can’t stop more than a half-century of shopping tradition.

Not when there are bargains to be had.

Early Thursday morning, dozens of deal-seeking folks from Lawrence and places elsewhere will start their pilgrimage to Massachusetts Street for the 51st annual Downtown Lawrence Sidewalk Sale, which will include cooling stations and portable toilets for visitor comfort.

The event officially runs from “sunup to sundown,” although several retailers — including Shark’s Surf Shop and Jock’s Nitch — had plans to open before dawn.

Throughout the day, more than 100 retailers and others will be working to clear inventory, freeing up shelf space and enticing shoppers with discounts, curious offerings and updated takes on old-time commercial entertainment.

The “barkers” at Sunflower Outdoor and Bike Shop are only part of the draw, said Cathy Hamilton, director of Downtown Lawrence Inc., the event’s organizer. Community groups will fan out to offer food and information. Borderline Country and other groups will perform at the corner of Ninth and Massachusetts streets.

Folks from the Topeka Zoo will be walking around with snakes, lizards, tortoises and other heat-tolerant critters.

“It’s a happening,” Hamilton said.

With the Lawrence area remaining under an excessive heat warning, organizers aren’t taking any chances. Shoppers will be able to visit several cooling stations to take breaks indoors, where free water will be available:

• The Eldridge Hotel, 701 Mass.
• Signs of Life bookstore, 722 Mass.
• Blue Dandelion, 841 Mass.
• US Bank, 900 Mass.
• Watkins Community Museum of History, 1047 Mass.

Portable toilets also will be available: two in the vacant lot adjacent to the Eldridge, and two in the breezeway in the 800 block of Massachusetts, immediately north of the Antique Mall.