Solar Flare Monitor: Live Solar Activity

Current X-ray flux: B5.4 (5.4e-7 W/m²)

NOAA SWPC, 2026-09-23 16:44 UTC. Refreshes every five minutes.

This page tracks one number: how brightly the Sun is shining in X-rays right now, measured by the GOES satellites and published by NOAA. That number is what a solar flare is. When a magnetic field on the Sun snaps into a simpler shape, the energy released heats plasma to tens of millions of degrees, and the X-ray flux jumps for anywhere from a few minutes to a few hours.

The classification is logarithmic, which is why it looks strange at first. Each letter is ten times brighter than the one before, so the difference between a C1 and an X1 is a factor of a thousand. Most days sit in the B or C range and nothing happens. An M flare is worth noticing. An X flare is worth watching, and the largest on record, in November 2003, saturated the sensors somewhere past X28.

The thing most people get wrong is the connection to aurora. A flare travels at the speed of light and reaches Earth in about eight minutes, and it produces no aurora at all. What produces aurora is a coronal mass ejection, a slower cloud of magnetised plasma that may or may not accompany a flare and may or may not be aimed at us. If one is, it arrives a day or three later, and you will see it first as a jump in solar wind speed and then as a rising Kp index.

Flare activity follows the roughly eleven-year solar cycle, and the current cycle has been running ahead of forecast, which is why X flares have been common enough recently to reach the general news. For what a given flare means for a night of observing, the honest answer is usually nothing at all, unless it came with a CME.

Solar flares FAQ

What do the letters A, B, C, M and X mean?
They are decades of X-ray brightness, each ten times the one below it. A and B are background, C flares are common and mostly harmless, M flares can cause brief radio blackouts on the sunlit side of Earth, and X flares are the strongest. The number after the letter is the multiplier inside that decade, so X2 is twice X1 and twenty times M1.
Does a solar flare mean I will see the aurora?
Not on its own. A flare is light and arrives in about eight minutes, and light does not cause aurora. What matters is whether the flare came with a coronal mass ejection aimed at Earth, which takes one to three days to arrive and shows up as a rise in solar wind speed and a southward Bz. Watch the Kp index for the geomagnetic response instead.
How current is the reading on this page?
It is the most recent long-band sample from the GOES X-ray sensor, published by NOAA SWPC and refreshed every five minutes. Flares are classified on the 0.1 to 0.8 nanometre channel, which is the one this page reads.
What does a flare actually affect?
The X-rays ionise the dayside upper atmosphere, which absorbs high-frequency radio. Aviation and marine HF users, and amateur radio operators, notice it first as a fadeout lasting minutes to an hour. Strong flares can also add noise to GPS and briefly upset satellite instruments. Nothing on the ground is at risk from the flare itself.

The rest of the space weather desk

The full space weather monitor carries every feed on one screen: scales and alerts, flare timelines, Kp history, solar wind plasma, sunspot regions, coronagraph frames and SDO imagery.

  • Kp index — The live planetary Kp, its G-scale storm level, and what it means for aurora.
  • Solar wind — Live speed, density and Bz from the DSCOVR spacecraft, roughly an hour upstream.
  • Aurora forecast — How far south the aurora reaches tonight, from the live Kp reading.