Scientists reported an X5.1-class solar flare on Nov. 11 that peaked around 5 a.m. EST, the strongest so far in 2025. The flare and its fast, energetic CME caused HF radio blackouts across Europe and Africa and disrupted high-frequency communications over the sunlit side of Earth. NOAA has issued a G3 watch and said it may raise the alert to G4 as two more CMEs are expected to arrive overnight.
X5.1 Solar Flare — Strongest of 2025 Sparks Radio Blackouts Across Europe and Africa
Scientists reported an X5.1-class solar flare on Nov. 11 that peaked around 5 a.m. EST, the strongest so far in 2025. The flare and its fast, energetic CME caused HF radio blackouts across Europe and Africa and disrupted high-frequency communications over the sunlit side of Earth. NOAA has issued a G3 watch and said it may raise the alert to G4 as two more CMEs are expected to arrive overnight.
03:53 AM, 11/12/2025Science
X5.1-class flare unleashes an energetic, fast-moving CME
Scientists reported that the Sun erupted early on Nov. 11, 2025, producing a powerful X5.1-class solar flare that peaked at about 5 a.m. EST. The outburst is the strongest recorded so far in 2025 and the most intense since October 2024.
The flare launched a fast, energetic coronal mass ejection (CME) that the National Oceanic and Atmospheric Administration (NOAA) described as 'quite energetic' and the 'fastest' observed so far from that sunspot group. The event produced high-frequency (HF) radio blackouts across Europe and Africa and interfered with HF communications over the sunlit portion of Earth.
NOAA said forecasters were 'evaluating the situation and will make any needed geomagnetic storm watch adjustments soon' and that two additional CMEs were expected to arrive overnight. A G3 watch is currently in effect under the official Space Weather Scales, indicating a strong chance of geomagnetic-storm impacts. If the watch is upgraded to G4, NOAA warned there would be a greater risk of widespread problems affecting electrical systems, communications and spacecraft operations; G5 is the highest level.
This X5.1 eruption followed other sizable flares recorded on Sunday and Monday. By comparison, a December 2023 flare — the largest since 2017 — briefly disrupted radio communications on Earth for about two hours and was described by the U.S. Space Weather Prediction Center as 'likely one of the largest solar radio events ever recorded.'
What to watch: Operators of HF-dependent systems, satellite teams and power-grid managers should monitor NOAA updates closely for potential watch upgrades and geomagnetic-storm impact forecasts.
Forecasters continue to track solar activity and will update guidance as new observations arrive.