Prediction of the Solar Polar Fields in 2026: An Unusually Weak Level across the Last Five Solar Cycles

Solar polar fields are essential for the solar cycle and the heliospheric magnetic field. Cycle 25 is now entering its declining phase, the critical period during which most of the cycle’s polar fields are established. Therefore, reliable polar-field prediction is now especially important. Polar-field evolution is governed by the poleward transport of already-emerged active-region (AR) flux over a timescale of a few years. Thus, surface flux-transport models can reliably provide 1 yr predictions without requiring information about future AR emergence. Our prediction method is validated using simulations of the surface magnetic field from 2020 to 2025 and hindcasts of the 2023–2024 polar fields, employing a newly constrained profile of the meridional flow. Using the most recent Helioseismic and Magnetic Imager synoptic magnetogram as the initial condition, we predict the polar-field evolution from 2025 October to 2026 October. The southern polar field is predicted to strengthen gradually, while the northern field is expected to decline sharply until 2026 March due to some ARs with abnormal polarity. By that time, the northern polar field becomes exceptionally weak, and the southern field remains relatively weak, raising concerns about the polar-field strength at the cycle 25/26 minimum and the amplitude of cycle 26.