| No. | Type | Alerts | Warnings | Watches |
|---|---|---|---|---|
| 1 | Kp Alert |
G2:
15:00 (UTC) on Wed 26 Mar 2025 to 18:00 (UTC) on Wed 26 Mar 2025 |
Space weather notifications explained
Different aspects of space weather have a variety of impacts on mankind and the technology we use. The Met Office Space Weather Operations Centre (MOSWOC) uses numbered scales developed by the National Oceanic and Atmospheric Administration (NOAA). These scales are similar to those used to describe hurricanes or earthquakes and are used worldwide to classify space weather conditions and communicate the impact on people and systems.
We have developed a UK-specific impact scale to use in forecasts, alerts and warnings based on the 2013 Royal Academy of Engineering report on the impacts of extreme space weather on engineered systems and infrastructures specific to the UK.
You can see the scales below for three different types of space weather:
- Radio blackouts (R Scale)
- Geomagnetic storms (G Scale)
- Solar radiation storms (S Scale)
Radio blackouts
The ionosphere is a dynamic part of the upper atmosphere which acts as a reflector for long-range, high-frequency communications (HF comms). During a solar flare, the increase in radiation from the sun causes the ionosphere to absorb rather than reflect signals, disrupting communications systems on the sunlit side of the Earth. The sun may also emit radio bursts at multiple wavelengths causing various problems for communication and navigation systems.
Even during periods of quiet solar activity, turbulence in the ionosphere can result in a scattering of electromagnetic waves disrupting navigation systems like Global Navigation Satellite Systems (GNSS) or Global Positioning System (GPS) and radio bands up to the GHz frequencies. These are referred to as radio blackouts.
| Category | UK effect * | US & global effect * | Physical measure | Average frequency (1 cycle - 11 years) | |
|---|---|---|---|---|---|
| Scale | Descriptor | GOES X-ray peak brightness by class and by flux | No. of events when flux level was met: (no. of storm days) | ||
| R5 | Extreme | HF Radio: Complete HF (high-frequency*) radio blackout on the entire sunlit side of the Earth, lasting for a number of hours. This results in no HF radio contact with mariners and en route aviators in this sector. | HF Radio: Complete HF (high-frequency*) radio blackout on the entire number of hours. This results in no HF radio contact with mariners and en route aviators in this sector.
Navigation: Low-frequency navigation signals used by maritime and general aviation systems experience outages on the sunlit side of the Earth for many hours, causing a loss in positioning. Increased satellite navigation errors in positioning for several hours on the sunlit side of the Earth, which may spread into the night side. |
X20
(2 x 10-3) |
Less than 1 per cycle |
| R4 | Severe | HF Radio: HF radio communication blackout on most of the sunlit side of Earth for one to two hours. HF radio contact lost during this time. | HF Radio: HF radio communication blackout on most of the sunlit side of Earth for one to two hours. HF radio contact lost during this time.
Navigation: Outages of low-frequency navigation signals cause an increased error in the positioning of satellite navigation possible on the sun side of Earth. |
X10
(10-3) |
8 per cycle
(8 days per cycle) |
| R3 | Strong | HF Radio: Wide area blackout of HF radio communications, loss of radio contact for about an hour on the sunlit side of Earth. | HF Radio:Wide area blackout of HF radio communication, loss of radio contact for about an hour on the sunlit side of Earth.
Navigation: Low-frequency navigation signals degraded for about an hour. |
X1
(10-4) |
175 per cycle
(140 days per cycle) |
| R2 | Moderate | HF Radio: Limited blackout of HF radio communication on sunlit side, loss of radio contact for tens of minutes. | HF Radio: Wide area blackout of HF radio communication, loss of radio contact for about an hour on the sunlit side of Earth.
Navigation: Low-frequency navigation signals degraded of about an hour. |
M5
(5 x 10-5) |
350 per cycle
(300 days per cycle) |
| R1 | Minor | HF Radio: Weak or minor degradation of HR radio communication on sunlit side, with occasional loss of radio contact. | HF Radio: Weak or minor degradation of HF radio communication on the sunlit side, with occasional loss of radio contact.
Navigation: Low-frequency navigation signals degraded for brief intervals. |
M1
(10-5) |
2000 per cycle
(950 days per cycle) |
** Other frequencies may be affected by these conditions
Geomagnetic storms
Geomagnetic storms are large disturbances in the Earth's magnetic field caused by changes in the solar wind and interplanetary magnetic field (IMF) structure. These changes in the solar wind arise from disturbances on the sun, such as in powerful coronal mass ejections (CMEs). Their effect can be felt for a number of days. With the right magnetic configuration, and increases in solar wind speed and density, large amounts of energy can be transferred into the Earth's geomagnetic system.
The effect of geomagnetic storms can result in impacts to power systems, spacecraft operations and other communication.
| Category | UK effect * | US & global effect * | Physical measure | Average frequency (1 cycle - 11 years) | |
|---|---|---|---|---|---|
| Scale | Descriptor | Kp values ** | No. of storm events when kp level was met; (no. of storm days) | ||
| G5 | Extreme | Power systems: Localised voltage control and protective system problems may occur, leading to the potential for localised loss of power. Transformers may experience damage.
Spacecraft operations: May experience extensive surface charging, drag may increase on low-Earth-orbit satellites, problems with orientation, uplink/downlink and tracking satellites. Other systems: HF (high-frequency) radio communication may be impossible in many areas for one to two days. GNSS (GPS) satellite navigation may be degraded for days with possible effects on infrastructure reliant on GSS (GPS) for positioning or timing. Low-frequency radio navigation can be out for hours, and aurora may be seen across the whole of the UK. |
Power systems: Widespread voltage control and protective system problems can occur. Some grid systems may experience complete collapse or blackouts. Transformers may experience damage.
Spacecraft operations: May experience extensive surface charging, drag may increase on low-Earth-orbit satellites, problems with orientation, uplink/downlink and tracking satellites. Other systems: Pipeline currents can reach hundreds of amps. HF (high-frequency) radio propagation may be impossible in many areas for one to two days. Satellite navigation may be degraded for days. Low-frequency radio navigation can be out for hours, and aurora has been seen as low as Florida and southern Texas (typically 40-degree geomagnetic lat).*** |
Kp = 9 | 4 per cycle
(4 days per cycle) |
| G4 | Severe | Power systems: No significant impact on UK power grid likely.
Spacecraft operations: May experience surface charging and tracking problems, drag may increase on low-Earth-orbit satellites, corrections may be needed for orientation problems. Other systems: HF radio propagation sporadic, GNSS(GPS) satellite navigation degraded for hours, low-frequency radio navigation disrupted, and aurora may be seen across the whole of the UK. |
Power systems: possible widespread voltage control problems and some protective systems will mistakenly trip out key assets from the grid.
Spacecraft operations: May experience surface charging and tracking problems, corrections may be needed for orientation problems. Other systems: Induced pipeline currents affect preventive measures, HF radio propagation sporadic, satellite navigation degraded for hours, low-frequency radio navigation disrupted, and aurora has been seen as low as Alabama and northern California (typically 45-degree geomagnetic lat.)*** |
Kp = 8, including a 9- | 100 per cycle
(60 days per cycle) |
| G3 | Strong | Power systems: No significant impact on UK power grid likely.
Spacecraft operations: Surface charging may occur on satellite components, drag may increase on low-Earth-orbit satellites, and corrections may be needed for orientation problems. Other systems: Intermittent GNSS(GPS) satellite navigation and low-frequency radio navigation problems may occur, HF radio may be intermittent. Aurora may be seen in Scotland and Northern Ireland and as low as Mid-Wales and the Midlands. |
Power systems: Voltage corrections may be required, false alarms triggered on some protection devices.
Spacecraft operations: Surface charging may occur on satellite components, drag may increase on low-Earth-orbit satellites, and corrections may be needed for orientation problems. Other systems: Intermittent satellite navigation and low-frequency radio navigation problems may occur, HF radio may be intermittent, and aurora has been seen as low as Illinois and Oregon (typically 50-degree geomagnetic lat).*** |
Kp = 7 | 200 per cycle
(130 days per cycle) |
| G2 | Moderate | Power systems: No impact on UK power grid.
Spacecraft operations: Corrective actions to orientation may be required by ground control; possible changes in drag affect orbit predictions. Other systems: HF radio propagation can fade at higher latitudes, and aurora may be seen across Scotland. |
Power systems: High-latitude power systems may experience voltage alarms, long-duration storms may cause transformer damage.
Spacecraft operations: Corrective actions to orientation may be required by ground control; possible changes in drag affect orbit predictions. Other systems: HF radio propagation can fade at higher latitudes, and aurora has been seen as low as New York and Idaho (typically 55-degree geomagnetic lat).*** |
Kp = 6 | 600 per cycle
(360 days per cycle) |
| G1 | Minor | Power systems: No impact on UK power grid.
Spacecraft operations: Minor impact on satellite operations possible. Other systems: Aurora may be seen as low as Northern Scotland. |
Power systems: Weak power grid fluctuations can occur.
Spacecraft operations: Minor impact on satellite operations possible. Other systems: Migratory animals are affected at this and higher levels; aurora is commonly visible at high latitudes (northern Michigan and Maine).*** |
Kp = 5 | 1700 per cycle
(900 days per cycle) |
** The Kp-index used to generate these messages is derived from a real-time network of observatories that report data to SWPC in near real-time. In most cases, the real-time estimate of the Kp-index will be a good approximation to the official Kp indices that are issued twice per month by the German GeoForschungsZentrum (GFZ) (Research Center for Geosciences).
*** For specific locations around the globe, use geomagnetic latitude to determine likely sightings
Solar radiation storms
In association with large solar flares, solar radiation storms may also occur. These storms, consisting of very high energy protons, primarily impact polar regions. This is called polar cap absorption, and their main effect is to degrade HF comms in these regions.
In space, astronauts and satellites can be exposed to increased levels of radiation. While extra-vehicular activity (spacewalks) can be avoided during a solar storm, satellites could be exposed to excessive and damaging radiation levels. For instance, solar panels can be degraded (reducing the life expectancy of the satellite), surface charging can damage the electronics and radiation can result in errors within computer systems.
Although the atmosphere provides a significant level of protection, charging and radiation from space weather events have been shown to impact ground-based systems occasionally. Similarly, aircraft, crews and passengers on high latitude polar routes may, on very rare occasions, be exposed to elevated radiation levels.
| Category | UK effect * | US & global effect * | Physical measure | Average frequency (1 cycle - 11 years) | |
|---|---|---|---|---|---|
| Scale | Descriptor | Flux levels of >= 10 MeV particles (ions) ** | No. of storm events when kp level was met; (no. of storm days) | ||
| S5 | Extreme | Biological: Passengers and crew in aircraft on certain routes may be exposed to increased radiation levels. The increase depends on the flight path and the detailed storm characteristics.****
Spacecraft operations: Some satellites may suffer temporary outages due to memory impacts, which can cause loss of control, serious noise in image data or orientation problems and permanent damage to solar panels. Aircraft operations: Some aircraft electronic systems may experience single events effects (SEE) which can cause upsets or unexpected behaviour. The rate of SEE depends on the flight path and the detailed storm characteristics. **** |
Biological: Unavoidable high radiation hazard to astronauts on EVA (extra-vehicular activity); passengers and crew in high-flying aircraft and high latitudes may be exposed to radiation risk. ****
Satellite operations: Satellites may be rendered useless, memory impacts can cause loss of control, may cause serious noise in image data, star-trackers may be unable to locate sources; permanent damage to solar panels possible. Aircraft operations: Pipeline currents can reach hundreds of amps. HF (high-frequency) radio propagation may be impossible in many areas for one to two days. Satellite navigation may be degraded for days, low-frequency radio navigation can be out for hours, and aurora has been seen as low as Florida and southern Texas (typically 40-degree geomagnetic lat).*** |
105 | Fewer than 1 per cycle |
| S4 | Severe | Biological: Passengers and crew in aircraft on certain routes may be exposed to increased radiation levels. The increase depends on flight path and the detailed storm characteristics.****
Satellite operations: Some satellites may suffer temporary outages, due to single event effects on electronics which can cause unexpected behaviours, noise in image data or orientation problems and permanent damage to solar panels.***. Aircraft operations: Some aircraft electronics systems may experience single event effects (SEE) which can cause upsets or unexpected behaviour. The rate of SEE depends on flight path and the detailed storm characteristics. **** |
Biological: Unavoidable radiation hazard to astronauts on EVA; passengers and crew in high flying aircraft at high latitudes may be exposed to radiation risk. ****
Satellite operations: May experience memory device problems and noise on imaging systems; star-tracker problems may cause orientation problems, and solar panel efficiency can be degraded. Aircraft operations: Blackout of HF radio communications through the polar regions and increased navigation error over several days are likely.*** |
104 | 3 per cycle |
| S3 | Strong | Biological: Passengers and crew in aircraft on certain routes may be exposed to increased radiation levels. The increase depends on flight path and the detailed storm characteristics.****
Satellite operations: A small number of satellites may experience outages due to single event effects, which can cause unexpected behaviours, noise on imaging systems and orientation problems. Aircraft operations: Some aircraft electronic systems may experience single event effects (SEE) which can cause upsets or unexpected behaviour. The rate of SEE depends on flight path and the detailed storm characteristics. **** |
Biological: Radiation hazard avoidance recommended for astronauts on EVA; passengers and crew in high-flying aircraft at high latitudes may be exposed to radiation risk. ****
Satellite operations: Single-event upsets, noise in imaging systems, and slight reduction of efficiency in solar panel are likely. Aircraft operations: degraded HF radio propagation through the polar regions and navigation position errors likely.*** |
103 | 10 per cycle |
| S2 | Moderate | Biological: No additional risk.****
Satellite operations: Infrequent single-event upsets possible. Aircraft operations: Unlikely to have significant effect. **** |
Biological: Passengers and crew in high-flying aircraft at high latitudes may be exposed to elevated radiation risk. ****
Satellite operations: Infrequent single-event upsets possible. Aircraft operations: Small effects on HF propagation through the polar regions and navigation at polar cap locations possibly affected.*** |
102 | 25 per cycle |
| S1 | Minor | Biological: None.****
Satellite operations: None. Aircraft operations: Unlikely to have an effect. **** |
Biological: None. ****
Satellite operations: None. Aircraft operations: Minor impacts on HF radio in the polar region.*** |
10 | 50 per cycle |
** Flux levels are 5-minute averages. Flux in particles.s-1.ster-1.cm-2. Based on this measure, but other physical measures are also considered
*** These events can last more than one day
**** High energy particle measurements (>-400 MeV) are a better indicator of radiation risk to aircraft avionics, passengers and crews. Pregnant women are particularly susceptible.
Types of notifications
The Met Office issues a number of different types of notifications triggered by space weather activity. These notifications fall into the following categories:
- A watch is a long lead time message for potential increases in geomagnetic activity only.
- A warning is issued when certain conditions are expected for a period of time.
- An alert is issued when an event threshold has been crossed.
- A summary is issued at the end of an event, confirming the start and end time and peak measurement during the event.
- Cancellation may be issued when either actual or forecast space weather conditions change to such an extent that the forecaster considers a watch or a warning is no longer valid.