Castle Hot Springs Debuts First-Ever Summer Season for 2026—Marking 130 Years with Seasonal Rates, Immersive Programming, and a Timely Nod to America’s 250th With affluent travelers increasingly rediscovering the depth and richness of U.S. destinations this summer, Castle Hot Springs enters a new chapter, debuting its first-ever summer season. For the first time in its 130-year legacy, the 1,100-acre Sonoran Desert retreat will remain open through July and August, introducing