State of the Geomagnetic Field 2025 December 2025 State of the Geomagnetic Field

This report reviews the performance of the latest WMM and WMMHR, released in December 2024 and referred to as WMM2025 and WMMHR2025. It also verifies that they continue to meet specification MIL-PRF-89500B (U.S. Department of Defense, 2019) as of January 1, 2026 (hereafter 2026.0; the same convention applies to other years), and provides an assessment of their secular variation after one year. This is the first such assessment of WMM2025 and WMMHR2025. In addition, this report reviews the five-year performance of the previous WMM, released in December 2019 and referred to as WMM2020. The most recent assessment of WMM2020 was conducted in December 2023 (NCEI & BGS, 2023). This report also describes notable changes in the Earth’s main magnetic field since WMM2025 and WMMHR2025’s release, including continued magnetic pole drift and the further deepening of the South Atlantic Anomaly in the geomagnetic field intensity. A separate section summarizes solar cycle progression and estimates the effects on WMM performance during magnetic storms.