Kerby Jean-Raymond, the founder of the independent, critically acclaimed fashion label Pyer Moss, planned to attend more than a dozen events at Art Basel Miami Beach this weekend, including an exhibition that showcases some of his label’s shoes.

Instead, he’ll be flying to North Dakota.

Mr. Jean-Raymond is among a number of designers and brands that are responding to the basic needs of demonstrators fighting to prevent the Dakota Access pipeline from being built near the Standing Rock Reservation out of concern for the environment and Native American ancestral lands.

Activists have requested nylon coveralls, heavy-duty sleeping bags, gloves, wool clothes and blankets, along with monetary donations, on their own websites and on Amazon.

After all, temperatures in Cannon Ball, N.D., the town near which protesters have gathered, range from highs in the low 30s to single digits. And it’s not about to get any warmer. On Monday, Gov. Jack Dalrymple of North Dakota cited “anticipated harsh weather conditions” when issuing a mandatory evacuation order.