Sun unleashes 2 colossal X-class solar flares, knocking out radio signals across the Americas and Pacific

two panel image showing the location of the two X-class solar flares from Nov. 4 2025.

The sun erupted with two X-class solar flares on Nov. 4, 2025. (Image credit: NASA SDO, annotated in Canva Pro by Daisy Dobrijevic)

The sun has fired off not one but two colossal X-class solar flares in less than 12 hours, causing radio blackouts across the sunlit portion of Earth at the time of eruption and marking a dramatic uptick in solar activity.

gif animation showing two big cme eruptions from the sun one streaming out to the upper left and the other lower right. — Each of the X-flares was accompanied by a coronal mass ejection. (Image credit: NOAA SWPC / LASCO)

The first eruption, an X1.8-class flare, exploded from sunspot AR4274 and peaked at 12:34 p.m. EST (1734 GMT). It triggered a strong R3 radio blackout across much of North and South America. A few hours later, at 5:02 p.m. EST (2202 GMT), a second X.1.1-class flare erupted from a region still hidden beyond the sun's southeastern limb, triggering another strong radio blackout across the North Pacific Ocean, New Zealand and parts of eastern Australia.

Both eruptions unleashed coronal mass ejections (CMEs) — vast plumes of magnetized plasma — but early modelling shows neither is directed at Earth. However, the outer edges of these CMEs could interact with a fast stream of solar wind later this week, sparking minor to moderate (G1-G2) geomagnetic storm conditions around Nov. 6-7, according to NOAA. This possible uptick in activity is good news for aurora chasers, as geomagnetic storms can result in some particularly vibrant and dynamic aurora shows.

What's next?

Sunspot AR4274 remains highly magnetically complex and is now turning to face Earth, meaning any future eruptions could be more Earth-directed. NOAA is currently forecasting a 65% chance of additional M-class flares and a 15% chance of X-class flares in the coming days.

But the activity hasn't stopped there! Just this morning (Nov. 5), the same active region AR4274 produced another strong M7.4-class flare, peaking at 6:15 a.m. EST (1115 GMT).

What is an R3 radio blackout?

On NOAA's five-level radio blackout scale (R1-R5), an R3 event is classified as strong. It is capable of disrupting high-frequency radio communications and navigation signals for up to an hour on the sunlit side of Earth. These blackouts can often affect aviation and maritime communications.

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Map showing radio blackouts across the Americas. The blackouts were triggered by the X1.8 solar flare on Nov. 4, 2025. — The X.1.8 solar flare caused radio blackouts across the Americas on Nov. 4. (Image credit: NOAA SWPC)

What are X-class solar flares?

A solar flare is a sudden, intense burst of energy from the sun caused by the sudden release of magnetic energy in an active sunspot region. These outbursts send radiation and charged particles hurling into space and can disrupt communications on Earth if the flare erupts from an Earth-facing sunspot.

X-class solar flares are the most powerful category of flare. The number that follows the X indicates its strength, with each step representing a coupling in power, meaning an X2 flare is twice as strong as an X1.

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Daisy Dobrijevic joined Space.com in February 2022 having previously worked for our sister publication All About Space magazine as a staff writer. Before joining us, Daisy completed an editorial internship with the BBC Sky at Night Magazine and worked at the National Space Centre in Leicester, U.K., where she enjoyed communicating space science to the public. In 2021, Daisy completed a PhD in plant physiology and also holds a Master's in Environmental Science, she is currently based in Nottingham, U.K. Daisy is passionate about all things space, with a penchant for solar activity and space weather. She has a strong interest in astrotourism and loves nothing more than a good northern lights chase!

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