Balloons are among the most frequent, and most often confirmed, explanations for UFO and UAP reports. The category spans weather balloons, large research balloons carrying instruments, latex and foil party balloons, and surveillance balloons. Because they drift with winds that change by altitude, catch sunlight after the ground is dark, can carry radar reflectors and seem stationary or fast depending on the observer's motion, balloons can mimic many features that witnesses and sensor operators find anomalous.

Balloons sit at the root of several foundational cases. The 1947 Roswell debris was publicly called a weather balloon within a day of the Army's "flying disc" announcement, and a 1995 Air Force report concluded it most likely came from Project Mogul, a classified program that flew microphones on high-altitude balloons to detect Soviet atomic tests; NYU Flight 4, launched June 4, 1947, came down near Roswell. In the Air Force's 1950s Battelle study, aircraft, balloons and astronomical objects accounted for 86 percent of identified reports. NSA intercept records released in 2026 after a Disclosure Foundation appeal assess many 1979 radar contacts as probably balloons.

Modern reporting keeps the pattern. The intelligence community's 2021 preliminary assessment identified only one of 144 reports with high confidence, as "a large, deflating balloon," and listed balloons among airborne clutter. Its 2022 annual report characterized 163 of 366 newly identified reports as balloon or balloon-like entities. AARO's fiscal 2025 report said it still resolves many cases as balloons, from foil party balloons to research balloons with tethered payloads. The February 2023 shootdown of a Chinese surveillance balloon off South Carolina, followed on February 10–12 by shootdowns over Alaska, Yukon and Lake Huron, showed both the security stakes and the identification problem; U.S. officials later said the last three were likely private objects unconnected to China.

Critics have long argued that the label is applied too readily. Astronomer J. Allen Hynek complained that Project Blue Book let "possible balloon" identifications harden into probable ones, and in 2026 UAP advocates mocked analyst Mick West's balloon readings of newly released Department of War videos, one of which he said was consistent with a small object in level flight at about 20 knots, perhaps a bird or a balloon. Balloons nonetheless remain the best-documented explanation in the UAP record: they anchor the official history of Roswell, account for a large share of cases resolved by the government and AARO, and sit at the center of the 2023 shootdowns of unidentified objects over North America.