Solar flare today
Live X-ray flare class from NOAA's GOES satellite, checked every minute.
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Illustration shown. The flare class is live data. A flare does not cause aurora by itself. If it launched a CME toward Earth, Kp can rise within about one to three days.
Flare chances, next 24 hours
X-ray flux, last 6 hours
Letters mark where each flare class begins. The line is the Sun's X-ray output on a log scale.
Source: NOAA Space Weather Prediction Center (GOES X-ray flux).
Solar flare today: what the Sun is doing and what it means
A solar flare today is a sudden burst of X-ray and radio energy from the Sun, and the live flare monitor above shows how strong the Sun's X-ray output is right now, while its flare chances are NOAA's forecast for the next 24 hours. This guide explains what the flare classes mean, how to read the gauge and chart, and what a flare can and cannot do to Earth, including whether it will bring the northern lights.
Flares are rated A, B, C, M or X by their peak X-ray strength, and each class is ten times stronger than the one before. On quieter days only A to C flares occur, and they are harmless on the ground. M- and X-class flares can cause radio blackouts on the sunlit side of Earth. A flare does not cause the northern lights by itself: aurora comes from CMEs and fast solar wind streams reaching Earth, and a CME launched by a flare usually takes one to three days to arrive.
- What a flare is
- Flare classes
- Reading the monitor
- Effects on Earth
- Flares, radiation and geomagnetic storms
- Flares and aurora
- How often flares happen
- Where to check
- Sources
What is a solar flare?
A solar flare is a rapid release of energy from the Sun's atmosphere, usually above a sunspot group where tangled magnetic fields suddenly reorganise. In minutes it can flood the solar system with radiation from radio waves through X-rays. That radiation travels at the speed of light, so the X-rays from a flare reach Earth in about eight minutes.
Flares are different from coronal mass ejections (CMEs), which are clouds of magnetised plasma thrown into space. The two often happen together, especially in strong events, but one does not guarantee the other.
Solar flare classes: A, B, C, M and X
NASA and NOAA rate flares by the peak X-ray flux measured by the GOES satellites in the 0.1 to 0.8 nanometre band. The scale is logarithmic, so each letter is ten times stronger than the one before it. The number after the letter is a multiplier within the class, so an M5 is five times as strong as an M1 and an X2 is twice an X1. Strength here means peak X-ray flux, not total energy released.
| Class | Peak flux (W/m²) | Typical effects |
|---|---|---|
| A | Below 10⁻⁷ | Background level. No noticeable effects. |
| B | 10⁻⁷ to 10⁻⁶ | Small flares. No noticeable effects. |
| C | 10⁻⁶ to 10⁻⁵ | Minor flares. Usually no noticeable effects on Earth. |
| M | 10⁻⁵ to 10⁻⁴ | Moderate flares. Can cause brief radio blackouts on the sunlit side of Earth. |
| X | 10⁻⁴ and above | Major flares. Can cause strong radio blackouts, and are often, but not always, associated with CMEs and energetic particle events. |
X-class has no upper limit. The strongest flare in the modern record, in November 2003, was estimated at roughly X28, and the detectors of the time were overwhelmed by it, so the exact figure is uncertain.
How to read the solar flare monitor
- The badge and glow. The class shown on the Sun is the latest X-ray reading from NOAA's GOES satellite. The monitor checks for new data every minute and GOES measurements are published at one-minute intervals, so there can be a short delay. The glow changes from grey to yellow, orange and red as the level rises, and it pulses during an M- or X-class flare.
- The gauge. It uses the same logarithmic scale as the classes, so each band is ten times the one below. The white line is the current level and the dashed line is the highest reading in the last six hours.
- The 6-hour chart. It plots the raw X-ray flux on a logarithmic scale, so you can see whether the level is rising or falling. It does not mark where individual flares start, peak and end. Flares usually rise within minutes and fade over minutes to hours.
- The 24-hour peak. The highest X-ray reading in the last 24 hours. It is usually the day's strongest flare, but on active days a flare that began earlier or an elevated background level can make it differ from the strongest individual flare.
- The flare chances. NOAA's forecast chance of C-, M- and X-class flares in the next 24 hours, shown as three separate forecasts rather than one combined number. These are forecasts, while everything else on the monitor is observed.
Two things to keep in mind. First, the badge shows the current level, while a flare's final class is set by its peak, so a flare that is still rising can end up stronger than the number you see. Second, the Sun's background X-ray level moves with the solar cycle, and near solar maximum it can sit in the B or C range even when no flare is in progress.
What the monitor cannot tell you
A live X-ray gauge measures flare radiation. It does not tell you whether a CME was launched, when it will arrive, how strong a geomagnetic storm will be, or whether you will see the northern lights from your city. For those, use the forecasts linked below.
Do solar flares affect Earth?
Earth's atmosphere and magnetic field protect people on the ground, and a flare is not a direct health risk to anyone here. The effects are on technology and on people in space or at very high altitude.
Radio blackouts
Flare X-rays ionise the upper atmosphere on the sunlit side of Earth, which absorbs high-frequency (HF) radio signals. NOAA rates the expected impact on its R-scale. The flare classes below are approximate peak-flux thresholds for each level, not a guarantee that every flare of that class will cause every listed effect.
| Level | Flare class | Typical effect on HF radio |
|---|---|---|
| R1 Minor | M1 | Weak degradation on the sunlit side, with occasional loss of contact. |
| R2 Moderate | M5 | Limited blackout on the sunlit side, with loss of contact for tens of minutes. |
| R3 Strong | X1 | Wide-area blackout on the sunlit side, with loss of contact for about an hour. |
| R4 Severe | X10 | Blackout on most of the sunlit side for one to two hours. |
| R5 Extreme | X20 | Complete blackout on the entire sunlit side for a number of hours. |
Radiation storms and satellites
Radio blackouts come from a flare's X-rays and begin within minutes. Separately, some eruptions accelerate energetic particles, mainly protons, which can reach Earth tens of minutes to several hours later. These solar radiation storms (NOAA's S-scale) can affect satellites and astronauts and can raise radiation levels on polar flight routes. Not every X-class flare produces one, because they can also come from shock waves driven by CMEs. Satellite navigation signals can also be briefly degraded during strong flares, depending on the flare and the system.
Flares, radiation storms and geomagnetic storms
NOAA treats these as three separate kinds of space weather event, each with its own scale. One eruption can trigger more than one, but they do not always occur together.
| Event | What it is | NOAA scale | How soon it reaches Earth |
|---|---|---|---|
| Solar flare | A burst of X-ray and radio energy | R-scale (radio blackouts) | About 8 minutes |
| Solar radiation storm | A surge of energetic particles, mainly protons | S-scale | Tens of minutes to several hours after the eruption |
| Geomagnetic storm | A disturbance of Earth's magnetic field, which produces aurora | G-scale | Hours to about three days, depending on the CME or fast stream |
Solar flares and the northern lights
A flare does not cause aurora by itself. The northern lights come from charged particles in the solar wind reaching Earth's magnetic field. CMEs are a major source of strong storms, but fast streams of solar wind from coronal holes can also drive aurora with no new CME at all. A flare's X-rays arrive in about eight minutes. A CME it launched typically takes one to three days to arrive, and some fast ones take less than a day. Whether it produces aurora depends on its speed and its magnetic field direction (Bz) when it arrives.
- Where the flare happened. A flare near the middle of the Sun's visible disc is more likely to send a CME toward Earth than one near the edge.
- Whether a CME followed. Many strong flares have no Earth-directed CME, and some CMEs come without a strong flare.
- What to check. Look at the Kp forecast together with NOAA's CME arrival predictions and its alerts, watches and warnings, rather than relying on Kp alone. For aurora specifically, see the northern lights forecast for tonight and the 3-day northern lights forecast for the next few nights.
How often do solar flares happen?
It depends on where the Sun is in its roughly 11-year cycle. Near solar minimum there can be weeks with no flare above B-class. Near solar maximum, C-class flares can occur daily, M-class flares several times a month or more, and X-class flares range from none in a quiet year to dozens in a very active one.
NASA and NOAA announced in October 2024 that the Sun had reached the solar maximum period of Solar Cycle 25. Activity declines gradually afterwards, but strong flares are still possible. The famous Halloween storms of October and November 2003, including that year's roughly X28 flare, came well after the peak of the previous cycle.
Where to check solar flares today
- This page. The monitor at the top checks NOAA's GOES X-ray data every minute.
- NOAA Space Weather Prediction Center. The official source for X-ray flux, alerts, watches and warnings, and the R, S and G scales.
- Sun images. NOAA's SUVI and NASA's Solar Dynamics Observatory show the Sun in ultraviolet light, where flares and active regions are visible. The Sun picture in the monitor is an illustration, and these colours are not what the eye would see.
- CME tracking. Coronagraph images from the SOHO spacecraft show CMEs leaving the Sun.