Solar flares on September 21, 2025
The most powerful solar flare in 24 hours
C6.6 (normal) flare - September 21 at 1:16 PM
Solar activity index
Value as of the end of the day on September 21, 2025
Solar X-ray emission over the past 2 days
Chart of solar X-ray emission (1-8 Å) from September 20, 2025 to September 21, 2025
Time zone — UTC-08 (Anchorage) — summer time
List of solar flares for September 21, 2025
The total number of solar flares of class C and higher — 7 flares
C class — 7 | M class — 0 | X class — 0
| Class | begin | max | end | region |
|---|---|---|---|---|
| C1.7 | 23:08 | 23:16 | 23:21 | 4217 |
| C6.6 | 13:04 | 13:16 | 13:20 | 4223 |
| C3.3 | 09:33 | 09:43 | 09:50 | 4224 |
| C2.3 | 09:01 | 09:08 | 09:14 | 4220 |
| C2.1 | 06:42 | 06:45 | 06:49 | 4217 |
| C1.6 | 03:55 | 04:03 | 04:20 | 4228 |
| C1.6 | 01:53 | 02:01 | 02:06 | 4217 |