Apple Watch Series 12 and Ultra 4 Leaked Features

New details about the upcoming Apple Watch Series 12 and Apple Watch Ultra 4 have emerged from leaked beta code, suggesting significant upgrades to health tracking, storage, and workout capabilities. The revelations, primarily sourced from analysis of watchOS 27 and iOS 27 beta builds by forum developer "pdfu," point to four key enhancements expected to be unveiled at Apple's "Surprise and Shine" press event scheduled for Wednesday, September 9, 2026. One of the most notable potential upgrades involves a new optical sensor family, referred to in the code as "Sunstone4p0." This hardware enhancement is anticipated to improve the accuracy of heart rate readings, particularly in challenging conditions where the pulse signal is weak. The new sensor appears designed with enhanced signal filtering and reduced electronic noise, potentially supporting continuous heart rate tracking more reliably. Internal storage is also reportedly set to double. Software profiles linked to the T8320 processor, believed to be the chip for the new models, indicate a jump to 1,024 gigabits, or 128GB, of storage.