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As of September 1, 2014, the NOAAWatch website will be discontinued. Active weather alerts will continue to be available 24/7 at Hurricane tracking widgets will continue to be available at and Learn about ways to get updates through social media at For information about how to reach other NOAA data and information, please email A temporary redirect of website traffic to NOAA’s homepage will exist for a short period of time after the shut-down of

UPDATE:  The NWS has replicated the NOAAWatch Briefing Page which can be found at

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Space Weather

Space weather describes the conditions in space that affect Earth and its technological systems. Space weather storms originate from the Sun and occur in space near Earth or in the Earth's atmosphere. These storms generally occur due to eruptions on the Sun known as solar flares and coronal mass ejections (CMEs). Rather than the more commonly known weather contributors of water, temperature, and air, solar storms are a result of changes in the continuous flow of solar particles and magnetic fields from the sun known as solar wind.

GOES solar X-ray image
The first image from the GOES-13 SXI was taken July 6, 2006. Learn more

Hurricanes and tsunamis are dangerous, and forecasting their arrival is a vital part of dealing with severe weather. Similarly, NOAA's Space Weather Prediction Center (SWPC) forecasts space weather to assist users in avoiding or mitigating severe solar storms. They provide real-time monitoring and forecasting of solar events; and, much like our weather offices around the country, they issue watches, warnings, and alerts for hazardous weather events. The SWPC is one of the nine National Centers for Environmental Prediction, part of the National Weather Service.

Technology is evolving at an incredible rate, especially our space-based technology. Many of these systems are vulnerable to hazardous space weather. The health of this Nation's technological infrastructure will depend heavily on our understanding of the space environment and our ability to predict hazardous solar storms. With the rising sophistication of our technologies, and the number of people that use technology, vulnerability to space weather events has increased dramatically. 

The Season of the Sun

The Sun, like Earth, has its seasons. The season of the Sun is based on sunspots and is known as the 11-year solar cycle (the Solar Minimum and Solar Maximum). Sunspots occur when strong magnetic fields emerge through the solar surface and allow the area to cool slightly, from a background value of 6000 degrees C down to about 4200 degrees C; this area appears as a dark spot in contrast with the Sun. These magnetically disturbed regions are often the source of large solar flares and subsequent coronal mass ejections from the Sun. This sunspot cycle is a useful way to mark the changes in the Sun. Solar Minimum refers to the several Earth years when the number of sunspots is lowest; Solar Maximum occurs in the years when sunspots are most numerous. During Solar Maximum, activity on the Sun and its effects on our terrestrial environment and technological systems are high.

Category of Solar Storms

Solar storms are categorized as: Geomagnetic Storms, Solar Radiation Storms, and Radio Blackouts. A geomagnetic storm is a disturbance in the geomagnetic field caused by gusts in the solar wind that blows by the Earth. A solar radiation storm is caused by elevated levels of solar radiation that occur when the numbers of energetic particles (protons) increase. A radio blackout is a disturbance of the ionosphere caused by X-ray emissions from the sun.

Geomagnetic Storms and Effects

GOES solar X-ray image
Auroral activity over the northern hemisphere extracted from NOAA POES data of December 19, 2006. More info

The aurora is a dynamic and visually delicate manifestation of solar-induced geomagnetic storms. The solar wind energizes electrons and ions in the magnetosphere. These particles usually enter the Earth's upper atmosphere near the polar regions. When the particles strike the molecules and atoms of thin, high atmosphere, some of them start to glow in different colors. The aurora begins between 60 and 80 degrees latitude. As a geomagnetic storm intensifies, the aurora can spread toward the equator. During an unusually large storm in 1909, an aurora was visible at Singapore, on the geomagnetic equator. The aurora provides pretty displays, but they are just a visible sign of atmospheric changes that may wreak havoc on technological systems.

Geomagnetic storms induce electrical currents that can have significant impact on electrical transmission equipment. Electric power companies have procedures in place to mitigate the impact of geomagnetic storms. However, in a worse-case scenario, a geomagnetic storm can result in a widespread blackout. On March 13, 1989, in Montreal, Quebec, 6 million people were without commercial electric power for 9 hours as a result of a huge geomagnetic storm. As recently as October 2003, power blackouts in Sweden and significant transformer damage in South Africa were attributed to geomagnetic storms. 

Many agencies relying on high-precision GPS (global positioning system) are familiar with the impact of geomagnetic storms on GPS accuracy. GPS errors can exceed 50 meters during the most intense storms. This is very significant to surveying and navigational systems. Those with the greatest concerns include the Federal Aviation Administration's (FAA) Wide-Area Augmentations System, land surveying companies using GPS measurements, deep-sea drilling operations, and land drilling and mining.  

Solar storms can also have significant impacts on the satellites we have come to rely on for everyday activities. Once rare and only government-owned, satellites are now numerous and carry weather information, military surveillance, TV and other communications signals, credit card and pager transmissions, navigation data, and cell phone conversations. Many satellites or instruments onboard satellites have been impacted by space weather in recent years. These storms can cause single event upsets which often cause physical damage to microchips and change software commands in satellite-borne computers. Other problems observed on satellites are contamination of the image systems, differential charging across the spacecraft components which can harm or possibly disable them, and increased drag on satellites in space causing them to slow and change orbit slightly.

Solar Radiation Storms and Effects

Solar radiation storms create a concern for passengers and crew of airlines, especially those flying the polar routes. Major airlines reroute flights away from the poles during big radiation storms. NASA too is concerned about the effects of solar radiation on astronauts. They are responsible for ensuring that the radiation exposure received by astronauts remains below established safety limits. During large storms crews on board the International Space Station (ISS) may relocate to portions of the ISS which are most shielded from higher levels of radiation. NASA may also power down the billion dollar robotic arm and workstation on the ISS, which are sensitive to radiation events. The concerns of solar radiation storms will be considerably greater when we do manned missions to the Moon, Mars, and beyond.

Radio Blackouts and Effects

Solar storms impact communications too. Radio blackout storms impacts to HF communications can be significant, resulting in degraded or impossible HF operations for hours, even days. Emergency response teams relying on HF communications can be impacted by solar storms. Airlines have long recognized the potential cost benefits of flying polar routes for the North America to Asia flights. By using these routes, airlines benefit from additional passenger revenue while producing significant savings on fuel and crew costs. Polar flights rely on HF communications for a large part of the route. The Federal Aviation Administration requires dispatchers to take into consideration HF communication degradation for each dispatched polar flight. Moderate to severe impacts due to solar radio blackout storms can have an affect on all HF groups and HF service. If the flight must divert for any reason, an additional stop-off is required. This results in considerable time loss, additional fuel, and the added time will require a whole new crew. The average cost for an airline for this kind of diversion increases significantly.   

A few of the Agencies and Industry that rely on SWPC services:

  • U.S. power grid infrastructure
  • Major airlines and other aviation groups
  • Department of Transportation (especially GPS users)
  • NASA human space flight activities
  • Satellite launch and on-orbit operations
  • HAM Operators and other communications groups
  • DoD
  • Commercial and public users (more than a million hits per day on SEC web sites)

Some Economic Impacts of Space Weather:

  • NASA relies on SEC data to protect the $1 billion arm on the International Space Station.
  • Space weather effects added $433 million to annual customer electricity costs in just one power pool.
  • $500 million in space asset claims from 1994-99 were attributed to, or aggravated by, space weather.
  • Airlines consideration of HF communication degradation for each dispatched polar flight. Flights can be diverted based on SEC solar radiation or geomagnetic storm alerts if air traffic control communication is compromised, with estimated costs as high as $100K per flight. A 23-day period in 2001 saw 25 flights diverted.


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