How Much Time Do We Have Before a G5 Geomagnetic Storm Hits After a Solar CME?

Color day time photo of a worried unhappy young black man reading g% Geomagnetic storm warning time of impact on his phone. City large building background.

Throughout the last century, and history, natural hazards have wrought catastrophic consequences worldwide. While geomagnetic storms are a less common natural hazard, a single event can cause immense global damage. As such, it’s crucial to be adequately prepared for these space weather events.

How much time do we have before a G5 Geomagnetic storm hits after a Solar CME? The time between a Solar CME and a G5 geomagnetic storm ranges from 12 to 36 hours. The 1859 Carrington event took about 17.7 hours to hit the earth. In 1972, a solar storm took 14.6 hours to hit earth and eventually blew up 4,000 Destructor Water Mines during the Vietnam War.

To understand how much notice we have before a G5 geomagnetic storm hits the earth after a CME, we must first look at the origin of these storms and a few recent Geomagnetic storms event effects.

What Are CMEs?

According to Live Science, geomagnetic storms originate from the sun. The sun is a formidable nuclear powerhouse, supplying us with light, heat, and energy. Due to its distance and extreme heat, this dynamic ball of fire remains a system we’re still learning to understand. 

Yet, advancements in heliophysics, the study of the sun, have shed light on the activities in its outer layer, the corona. Understanding the corona is fundamental to grasping the origin of CMEs. A coronal mass ejection (CME) consists of many fast-moving electrically charged particles from the sun’s upper atmosphere, the corona. 

Occasionally, significant portions of the sun’s electromagnetic field and plasma erupt violently from the corona. This eruption sends high-energy x-rays and extreme ultraviolet radiation hurtling toward other parts of the solar system. 

Accompanying this wave is a massive, hot bubble filled with charged gases and solar energetic particles (SEPs). Together, at their point of origin, they constitute a CME. Once free from the sun’s gravitational influence, CMEs can achieve speeds of hundreds of miles per second.

How Big Are Coronal Mass Ejections (CMEs)?

The size of Coronal Mass Ejection or CME is contingent on the magnitude of the eruption. According to NASA’s Polar, Wind and Geotail Missions, a substantial CME is estimated to carry up to a billion tons of matter, hurtling at several million miles per hour

As CMEs journey away from the sun, they expand, growing exponentially in size. By the time they reach Earth’s orbit, these tumultuous spheres of storm can span up to 25 million kilometers in diameter (40 million kilometers), approximately a quarter of the distance between Earth and the sun. 

As the Space Weather Prediction Center reports, their vast expanse indicates their potential havoc on the solar system. Imagine a nuclear bubble potent enough to obliterate a star or planet in its trajectory. Fortunately, as far as we know, throughout its history, Earth has evaded a direct hit from a significant solar CME.

Are All CMEs a Threat to Earth?

Color outdoor photo of a portion of the U.S. power grid, electrical lines and tower, and large power transformers.
A portion of the U.S. power grid, electrical lines and tower, and large power transformers that could be affected by a G5 Geomagnetic Storm.

The sun produces, on average, about three solar storms daily. Fortunately, many of these eruptions don’t even reach the sun’s orbit or approach its atmosphere. Our primary concern is with the CMEs that align with Earth’s orbit and pose a potential impact. 

When a CME interacts with our atmosphere, it instigates temporary disturbances in our planet’s magnetic fields, known as geomagnetic storms. According to, such storms can adversely affect the following: 

  • Power grids
  • Radio communications
  • Satellite systems
  • Other terrestrial electromagnetic systems 

The greatest danger we have from a G5 Geomagnetic storm or stronger is it’s effect on the worlds Power Grids. If a Carrington class event or stronger hit the earth the U.S. power grid could be shut down for days, weeks, or years and is a grave danger to all of humanity.

Nothing in society would work after a few weeks with the power grids off line. No gasoline, municipal water, or food would be available after only a month with no power.

These disturbances occur because the storms change Earth’s magnetic fields and heighten ground conductivity. This combined effect produces magnetic fluxes potent enough to disrupt both power transmission and communication systems.

What Is a G5 Geomagnetic Storm?

A multi colored vector image illustration of a G5 geomagnetic storm showing the earths magnetic field blocking and being penetrated by the storm.
G5 geomagnetic storm showing the earths magnetic field blocking and being penetrated by the storm.

A G5 geomagnetic storm is an intense geomagnetic disturbance classified as “Extreme” on the National Oceanic and Atmospheric Administration’s (NOAA) 5-point Geomagnetic Storms Rating Scale. 

While these events are uncommon, when they occur, they result in significant disruptions to power transmission and communication systems. Affected power grid transmission systems can face widespread voltage control problems, and some grids might experience total collapse

High-voltage power transformers risk damage, potentially disabling entire power networks and leading to citywide blackouts (source). The electromagnetic interference produced by these storms can severely disrupt radio transmissions, rendering them inoperative on a global scale for several days. Satellite systems aren’t spared either, and disruptions may affect satellite navigation for a day or two, severely hindering the aviation industry. 

The NOAA Space Weather Prediction Center reports such storms are infrequent, occurring only about four days in every 11-year solar cycle. Predictions suggest these storms might become more prevalent in the forthcoming years as the sun transitions into the peak phase of its 11-year cycle.

Have We Experienced G5 Storms Before?

Indeed, we have had G5 storms in the past. According to, the most notable geomagnetic storm to impact Earth was the Carrington event of 1859. This immense solar storm disrupted telegraph services worldwide and produced auroras visible as far away as the Bahamas. 

On August 4, 1972, an extremely strong solar flare occurred hitting the earth. During the Vietnam war in North Vietnam near the port of Hai Phong. Out of approximately 8,000 Destructor sea mines near the port, 4,000 exploded in little more than a few weeks due to the geomagnetic storm according to the U.S. Navy.

However, other storms of lesser magnitude but still of significant impact have been recorded. For instance, NASA reports that the October-November 2003 “Halloween” event disrupted the aviation industry, power transmissions, and satellite communications. 

Another noteworthy event was the 1989 Quebec blackout, which affected Canadian and U.S. power systems by damaging extra high-voltage transformers.

Should We Expect a G5 Storm in the Future?

Color vector image of a satellite in the earths atmosphere with the sun and space in the background.
A satellite in the earths atmosphere with the sun and space in the background.

Yes, we will absolutely experience more G5 geomagnetic storms in the future. The sun goes through regular activity cycles, including producing solar flares and coronal mass ejections (CMEs). While not all of these solar eruptions align with Earth or possess the intensity to cause a G5 storm, the historical record, like the Carrington event of 1859, shows that such powerful storms have and will occur. 

As our dependence on electronic and satellite-based technology grows, it’s essential to monitor solar activity and prepare for potential geomagnetic disturbances, even if they are rare. Researchers continue to study the sun’s patterns to better predict and understand the potential impact of future geomagnetic storms on our planet.

How Should We Prepare for a G5 Storm?

Color photo of emergency preparedness supplies and backpack on a table on a living room table.
Emergency preparedness supplies and backpack on a table on a living room table.

Space weather events, such as G5 storms, can profoundly impact power systems and advanced technologies integral to our daily lives. One of the most crucial measures to prepare for a G5 storm or other extreme space events is to assemble or stock up emergency preparedness supplies and develop a communication plan

Given the potential for power grid outages during a G5 storm, it’s essential to prepare these supplies well in advance. As mentioned, there’s a window of 12-36 hours to brace for a G5 storm once detected. 

Please see our articles “How to Protect Electronics from Severe Weather” and  “What To Do Before a G5 or Greater Geomagnetic Storm?”

Key steps to take during this timeframe include:

Establish Communication With Family and Loved Ones

Effective communication can be the difference between safely navigating a disaster and facing potential risks. Upon hearing about an impending G5 storm, immediately contact all your family to relay the information. 

If possible, create and share a communication plan detailing how you’ll communicate during the emergency. Also, decide on a secure location for the family to take refuge during the event. Basements and or upper-floor rooms are often chosen as safe havens during emergencies.

Develop an Emergency Response Action Plan

Color photo of a emergency preparedness checklist with a writing pen laying on top.
Emergency preparedness checklist with a writing pen laying on top.

This plan should detail how you and your family react to the G5 storm. Factors to consider include: 

  • Where the family will meet. 
  • The role of each member to ensure safety during the storm. 
  • Your designated shelter location. 
  • Procedures for potential emergency scenarios.

Compile a Family Contact List

This list should contain the contact information for all family members. Also, include names and contacts of one or two out-of-town individuals who can physically reach the family after the storm.

Ensure Access to an Emergency Preparedness Kit

Color photo of multiple stacked 5 gallon water containers in a home storage area.
Multiple stacked 5 gallon water containers in a home storage area.

An emergency kit holds crucial supplies to help you navigate through trying situations. This kit should be easily accessible. Suggested items for an emergency preparedness kit include: 

  • Water: at least one gallon (4 liters) per person daily. 
  • Food: a three-day supply of non-perishable items. 
  • Battery-powered or hand-crank radio with NOAA Weather Radio alerts. 
  • Flashlight, first aid kit, soap, disinfectant, extra batteries, whistles, dust mask, wrench or pliers (for utilities), local maps, cell phones with chargers, matches, and flares.

Consider protecting sensitive items in airtight plastic bags and ensure the kit is accessible to everyone.

Gather Additional Necessary Supplies

With the likelihood of power outages, ensure your car’s tank is at least half full. Other useful supplies might include: 

  • Fire extinguisher 
  • Books and novels 
  • Activities for children like puzzles 
  • Cash or traveler’s checks 
  • Pet food 
  • Dual-fuel backup generator 
  • Alternative power sources, e.g., solar generator 
  • Feminine hygiene products 
  • Extra clothing

Stay Informed

Color photo of an emergency solar hand crank weather radio charging a cell phone and with earbuds plugged into it.
Emergency solar hand crank weather radio charging a cell phone and with earbuds plugged into it.

Continuously monitor the latest updates on the approaching G5 storm. Sources like NOAA alerts, radio broadcasts, and online websites provide regular updates on the storm’s progress.

Take Swift Action

Once the storm is imminent, implement your emergency response plan. Move to your designated safe spot, turn off the main power to your home from the electrical panel, and check on the safety of friends and neighbors.

Key Takeaways

A green sign with the words "Are You Ready?" printed in black bold letters underlined with a red line and showing a red felt tip pen in the picture.

Space storms pose an ever-present risk that, while beyond our control, can be predicted. The 12-36 hour window between a CME’s detection and the arrival of a geomagnetic storm on Earth does not provide ample time to react unless you are prepared in advance. 

Given the unpredictability of a storm’s duration, it’s prudent to be well-prepared and adequately stocked. It could take several days, weeks, or years, to address the aftermath of a G5 geomagnetic storm, so advance readiness is crucial. As the saying goes, “Better safe than sorry.”


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John Mortensen

As a kid I wanted to be an astronaut, geologist, or scientist. I became a project manager which is involved with many of those things. I am a project manager and tech writer who researches the latest alternative and green technologies. We write helpful articles about green electronics and green technology products. AI, extreme weather, electric vehicles, are all in our future and we want to know the best way to deal with the effects of these on the power grid and emergency preparedness.

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