Viewing archive of Saturday, 20 September 2025
Solar activity report
Report of Solar-Geophysical Activity 2025 Sep 20 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 263 Issued at 2200Z on 20 Sep 2025IA. Analysis of Solar Active Regions and Activity from 19-2100Z to 20-2100Z Solar activity has been at moderate levels for the past 24
hours. There are currently 10 numbered sunspot regions on the disk.
IB. Solar Activity Forecast
Solar activity is expected to be low with
a chance for M-class flares on days one, two, and three (21 Sep, 22 Sep,
23 Sep).
IIA. Geophysical Activity Summary 19-2100Z to 20-2100Z
The geomagnetic
field has been at quiet levels for the past 24 hours. Solar wind speed
reached a peak of 457 km/s at 19/2100Z. Electrons greater than 2 MeV at
geosynchronous orbit reached a peak level of 4444 pfu.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected
to be at unsettled to active levels on day one (21 Sep), unsettled to
minor storm levels on day two (22 Sep) and quiet to unsettled levels on
day three (23 Sep).
III. Event Probabilities 21 Sep to 23 Sep
| Class M | 40% | 40% | 40% |
| Class X | 05% | 05% | 05% |
| Proton | 05% | 05% | 05% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 20 Sep 166 Predicted 21 Sep-23 Sep 165/170/170 90 Day Mean 20 Sep 145
V. Geomagnetic A Indices
Observed Afr/Ap 19 Sep 007/003 Estimated Afr/Ap 20 Sep 005/005 Predicted Afr/Ap 21 Sep-23 Sep 015/018-019/024-009/012
VI. Geomagnetic Activity Probabilities 21 Sep to 23 Sep
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 30% | 40% | 20% |
| Minor storm | 10% | 25% | 05% |
| Major-severe storm | 01% | 05% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 15% | 10% | 15% |
| Minor storm | 30% | 25% | 25% |
| Major-severe storm | 40% | 60% | 25% |
All times in UTC
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Space weather facts
| Last X-flare | 2025/12/01 | X1.9 |
| Last M-flare | 2025/12/06 | M8.1 |
| Last geomagnetic storm | 2025/12/04 | Kp5 (G1) |
| Spotless days | |
|---|---|
| Last spotless day | 2022/06/08 |
| Monthly mean Sunspot Number | |
|---|---|
| November 2025 | 91.8 -22.8 |
| December 2025 | 167.7 +75.9 |
| Last 30 days | 107.1 +13.7 |