BKG

Space Weather

Situation Report, January 21, 2026

Overall Situation
4 /5
Severe
ⓘ Explanation of the WESIS Space Weather Scales at the end of the document
Classifications
Geomagnetic Disturbance start: January 20, 06:00 UTC
duration: 24.0 hours
G4
Severe
Disturbance Storm start: January 19, 21:00 UTC
duration: 35.0 hours
D4
Severe
Solar Radio Flux start: January 18, 17:39 UTC
duration: 2.1 hours
F2
Moderate
Proton Flux start: January 18, 22:55 UTC
duration: 40.5 hours
S4
Severe
Electron Flux start: January 18, 06:10 UTC
duration: 3.5 hours
E2
Moderate
X-Ray Flux start: January 18, 17:49 UTC
duration: 115 minutes
R3
Strong
Warnings

Energy Supply

Space Operations

Communication

Navigation

Flight Crew

Solar surface
This image, taken with the Wettzell Solar Optical Telescope (WSOT), shows the active solar region AR 4341, which consists of several sunspots. This active region is responsible for a sharp increase in solar activity in the days that follow.
Operational Comments
January 19, 2026: On Sunday, January 18, 2026, an X1.9 flare occurs, peaking at 18:09 UTC. The flare originates from Region 4341. In the X-ray spectrum, the R3 threshold is briefly exceeded.
January 19, 2026: GOES imagery indicates that the CME was ejected in the direction of Earth. Based on this, increased geomagnetic activity is expected in the coming days.
January 19, 2026: Update: On Monday, January 19, 2026, the S3 threshold (proton flux) will be exceeded starting around 10 UTC.
January 20, 2026: Update: The proton flux reached the S4 threshold with a maximum reading of 37,000 PFU at approximately 19:30 UTC.
January 20, 2026: Update: Based on the recorded X1.9 flare, the CME has now reached Earth and caused a G4-class geomagnetic disturbance. The effects are currently ongoing. Observers believe that, under the current circumstances, a G5-class event could also occur.
January 20, 2026: Yesterday, January 19, 2026, shortly after 21:00 UTC, the DSCOVR satellite at the L1 point measured a sudden surge in the solar wind from 300 km/s to over 1,000 km/s (see DSCOVR image).
January 20, 2026: A distinctive feature of this space weather event is the exceptionally strong proton flux from the Sun. It is a combined flare-CME event (a coronal mass ejection—CME—often follows a strong flare or is triggered by it). The flare initially releases the heavy proton particles, which are then amplified by the CME. Factors such as the Sun’s magnetic field configuration, the position of the active region (ideally at the center of the solar disk), and the phase of the solar cycle (we are near the peak of Cycle 25) influence the intensity. This specific S4 proton storm intensified on January 19, 2026, and was triggered by an X1.9-class flare from sunspot region AR 4341 on January 18. The flare was one of the strongest in recent years and generated a full-halo CME, a massive plasma cloud traveling at speeds exceeding 1,000 km/s, which reached Earth in just about 25 hours—an unusually short time. The protons were likely accelerated directly by the magnetic reconnection process of the flare and further amplified by the CME shock, which explains the comparatively rapid rise and the high flux values. This is the strongest solar radiation storm since October 2003 (the famous "Halloween storms" of Cycle 23)—that is, the strongest in over 20 years. The electron flux is also elevated, but not as dramatically, since particle acceleration in this case has favored protons. Electron fluxes often increase as well, but typically reach lower peaks in proton-dominated events, as electrons are more easily scattered or slowed down. The associated CME also triggered a separate G4 geomagnetic storm, which can lead to strong auroras (visible even at mid-latitudes). The S4 event may pose risks to satellites, polar flights, and astronauts, but it has little impact on people at ground level.

Examples of Effects

  • Energy supply: Widespread problems with the control of high-voltage grids are possible; certain protection systems may incorrectly disconnect key components from the grid; induced currents in pipelines are possible.
  • Space operations: Electrostatic charging of satellite surfaces is likely; corrective measures for satellite orientation will be necessary. Problems with memory modules and increased image noise are possible; negative effects on the star tracker may lead to orientation problems; the efficiency of the solar panels may be reduced. Slightly increased likelihood of deep-dielectric charging.
  • Communication: HF radio communication may now only be possible sporadically; LF radio connections have been interrupted. HF radio blackouts in polar regions. Widespread HF radio blackouts on the sunlit side of the Earth; loss of contact with ships and aircraft.
  • Navigation systems: Satellite navigation systems can be disrupted for hours. In rare cases, false echoes may occur in radar systems used for airspace surveillance. Increased positioning errors in navigation systems may occur over several days. Low-frequency navigation signals in maritime and aviation were disrupted for about an hour.
  • Flight crew: There is a risk of cosmic radiation for passengers and crew members on flights near the pole.
Measurement of X-Rays
The U.S. National Weather Service's geostationary satellites measure the X-ray flux. The x-axis represents time in the format Day.Month HH:MM UTC. The y-axis shows X-ray radiation in [W/m²] in the wavelength range from 0.1 to 0.8 nm.
Proton flux measurements
The U.S. National Weather Service's geostationary satellites measure the proton flux. The x-axis represents time in the format Day.Month HH:MM UTC. The y-axis shows the proton flux in [particles/cm²/s/sr] (protons with energies above 10 MeV).
DSCOVR
The DSCOVR satellite is located at the L1 Lagrange point, about 1.5 million kilometers from Earth, where it measures the speed and temperature of the solar wind.
Disturbance Storm Index Dst
Similar to the Kp index, the Dst characterizes geomagnetic activity. However, here the equatorial ring current is calculated using four geomagnetic observatories distributed at regular intervals. The x-axis represents time in the format Day.Month HH:MM UTC. The y-axis displays the DST index value in [nT]. Warning thresholds defined internally by GOW are plotted as needed.
Planetary K-index
Each vertical line represents the Kp index for the corresponding 3-hour interval. The x-axis represents time in the format Day.Month HH:MM UTC. The y-axis shows the index value. Warning thresholds from the NOAA Space Weather Prediction Center (SWPC) are plotted as needed.
WESIS Space Weather Scales

The warning scale is based on the scale used by the National Oceanic and Atmospheric Administration (NOAA, USA) and comprises five levels, ranging from 1 (mild) to 5 (extreme). Statistically, extreme events occur one to four times per solar cycle. A cycle lasts 11 to 13 years.

D | Disturbance Storm Time (Dst) Index

The Dst Index is a primary gauge for geomagnetic storm severity, derived from a worldwide network of near-equatorial magnetometer stations. It calculates the globally averaged disturbance in the horizontal (H) component of Earth's magnetic field. As solar storms inject energetic ions into the magnetospheric ring current, they create a magnetic field that directly opposes Earth’s field, pushing Dst values deeply negative.

D1 < -50 nT
D2 < -75 nT
D3 < -100 nT
D4 < -200 nT
D5 < -400 nT
E | Electron Flux

The NOAA SWPC tracks the outer radiation belt using geostationary GOES satellites to issue Electron Flux Alerts. Warnings are activated when the >=2 MeV electron flux exceeds 1,000 pfu for three consecutive 5-minute intervals. This indicator warns operators of deep-dielectric charging, where accumulated internal electrical charges in spacecraft components can cause sudden arcing, leading to phantom commands or permanent satellite damage.

E1 1.000 electrons/ second
E2 10.000 e/s
E3 100.000 e/s
E4 1.000.000 e/s
E5 10.000.000 e/s
F | Solar Radio Flux

A parameter to which we actively contribute using the Solar Flux Telescope (CLT). Similar to the case of X-rays (see R-scale), the amounts of energy emitted during solar flares are reflected in the measurements of solar energy flux as so-called radio bursts. If the measurements increase abruptly, they are converted to the warning scale according to the following scheme: Increase in solar flux greater than:

F1 500 sfu
F2 1.000 sfu
F3 10.000 sfu
F4 20.000 sfu
F5 40.000 sfu
G | Geomagnetic Storms

The NOAA SWPC uses the G-Scale to categorize the severity of Geomagnetic Storms caused by solar wind variations. The scale directly maps to the planetary Kp-index, ranging from G1 (Kp = 5) up to G5 (Kp = 9). It serves as a vital operational warning system for power grid operators regarding transformer damage, pipeline engineers tracking corrosive currents, and satellite flight dynamics teams monitoring increased atmospheric drag and surface charging.

G1 Kp5
G2 Kp6
G3 Kp7
G4 Kp8
G5 Kp9
I | Electron Content

Total Electron Content (TEC) is the integrated electron density along a signal path through Earth's ionosphere, measured in TEC Units (TECU). Rapid increases in TEC, driven by solar EUV/X-ray flares and geomagnetic storms, directly modify the refractive index of the upper atmosphere. This causes signal phase delays and range errors for Global Navigation Satellite Systems (GNSS/GPS), high-frequency (HF) radio degradation, and satellite-to-ground communication disruptions, making it a critical metric for precision aviation and maritime navigation. We determine the total electron content using our own GNSS measurements.

I1 40 TECU
I2 50 TECU
I3 60 TECU
I4 70 TECU
I5 85 TECU
R | X-Ray Flux

The NOAA SWPC uses the R-Scale to categorize Radio Blackouts caused by sudden solar flare X-ray emissions. The primary metric is the peak X-ray flux measured in by GOES satellites, mapping directly to flare classes from R1 (M1 class) up to R5 (X20 class). It warns maritime, aviation, and military operators of sudden ionospheric absorptions that block HF radio communication and cause positioning errors in low-frequency navigation systems.

R1 0.00001 W/m² (M1 Flare)
R2 0.00005 W/m² (M5 Flare)
R3 0.0001 W/m² (X1 Flare)
R4 0.001 W/m² (X10 Flare)
R5 0.002 W/m² (X20 Flare)
S | Proton Flux

The NOAA Space Weather Prediction Center (SWPC) uses the S-Scale to categorize Solar Radiation Storms. The primary metric is the elevated proton flux (>=10 MeV), measured in Particle Flux Units (pfu) by GOES satellites. Stoms range from S1 (>=10 pfu) to S5 (>=100,000 pfu). It warns industries of polar HF radio communication failures, spacecraft orientation errors, and heightened radiation hazards.

S1 10 protons/second
S2 100 p/s
S3 1.000 p/s
S4 10.000 p/s
S5 100.000 p/s