Last month saw the publication of the 2025 State of the Geomagnetic Field Report. The report details the current state of Earth’s main magnetic field, and provides a performance analysis of the most recent version of the World Magnetic Model (WMM) released in late 2024, known as WMM2025. The report also assesses the performance of the newly developed World Magnetic Model High Resolution (WMMHR2025), a high-resolution version of the model that debuted alongside WMM2025. Comparisons between the predictions of the two models and recent data collected from the European Space Agency (ESA)’s Swarm satellites indicate that WMM2025 and WMMHR2025 have proven in their first year of operation to be accurate models.
Most of our planet’s magnetism originates from the shifting of electrically charged molten metals in its outer core, the behavior of which is unpredictable. An example of the secular changes that these metals can cause is the slow drifting of Earth’s magnetic north pole towards Siberia, a process that has been occurring continuously for the past few decades. As the WMM is predictive in nature, it becomes less accurate over time and must be updated with the newest projections derived from more recently collected data. Updates are scheduled to occur every five years.
The WMM is a joint project between NOAA’s National Centers for Environmental Information (NCEI) and the British Geological Survey (BGS). It is utilized by these agencies’ respective governments for their navigation, attitude, and heading software. In terms of military applications, the WMM proves indispensable for undersea and aircraft navigation as well as parachute deployment, antenna tracking, iceberg drift determination, and many other activities. In the private sector, the model can be found in virtually every smartphone. The Federal Aviation Administration also uses it to rename airport runways so that they accurately reflect their magnetic heading to allow for greater clarity during landing procedures.
This year’s report contains discussions of the two magnetic poles and their drift speeds. Over the past year, the northern magnetic pole has been traveling at a much faster rate than the southern pole with their average drift speeds measuring 36 km/year and 9 km/year, respectively. The actual locations and drift speeds of the magnetic poles proved to be very close to those predicted by WMM2025 and WMMHR2025, lending further credence to the overall accuracy of the models.
The South Atlantic Anomaly Grows
Also described in the State of the Magnetic Field Report is the deepening of the South Atlantic Anomaly (SAA), an area spanning the South Atlantic Ocean and South America where the Earth’s magnetism is weakest. This area is known to cause radiation damage to satellites and problems with radio propagation, issues that are exacerbated by the SAA’s growth in size by eight percent over the past year. NCEI continues to monitor the situation closely.
A well-known limitation of the WMM is the tendency for its accuracy to drop during magnetic storms, of which there were 18 that were strong to severe between November 1, 2023 to October 31, 2025. These space weather events can cause disparities between actual magnetic declination and the estimated declination provided by the WMM that are temporarily greater than the model uncertainty, especially at high latitudes. Such disparities can potentially affect navigation that relies on WMM2025 and WMMHR2025’s declination estimates. This year’s report includes descriptions of the two largest storms in order to alert users to this limitation to the models. Although Solar Cycle 25 has already passed its peak, space weather activity is expected to remain elevated for the next few years before gradually declining toward the anticipated solar minimum around 2030. Fortunately, the models take space weather into account in their error estimates.
Regardless of these minor concerns, all data gathered for the annual report indicates that WMM2025 and WMMHR2025 have operated well below the margin of error stipulated by the U.S. Department of Defense. The models can thus continue to be relied on by all technology that implements them.