Viewing archive of Wednesday, 17 September 2025
Solar activity report
Report of Solar-Geophysical Activity 2025 Sep 17 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 260 Issued at 2200Z on 17 Sep 2025IA. Analysis of Solar Active Regions and Activity from 16-2100Z to 17-2100Z Solar activity has been at low levels for the past 24 hours.
There are currently 6 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 (18 Sep, 19 Sep,
20 Sep).
IIA. Geophysical Activity Summary 16-2100Z to 17-2100Z
The geomagnetic
field has been at quiet to unsettled levels for the past 24 hours. Solar
wind speed reached a peak of 872 km/s at 17/0843Z. Total IMF reached 5
nT at 17/0008Z. The maximum southward component of Bz reached -4 nT at
17/0704Z. Electrons greater than 2 MeV at geosynchronous orbit reached
a peak level of 4335 pfu.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected
to be at quiet to unsettled levels on day one (18 Sep) and quiet levels
on days two and three (19 Sep, 20 Sep).
III. Event Probabilities 18 Sep to 20 Sep
| Class M | 35% | 35% | 35% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 17 Sep 147 Predicted 18 Sep-20 Sep 148/150/150 90 Day Mean 17 Sep 144
V. Geomagnetic A Indices
Observed Afr/Ap 16 Sep 017/021 Estimated Afr/Ap 17 Sep 010/011 Predicted Afr/Ap 18 Sep-20 Sep 009/010-006/005-006/005
VI. Geomagnetic Activity Probabilities 18 Sep to 20 Sep
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 20% | 10% | 10% |
| Minor storm | 05% | 01% | 01% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 15% | 15% | 15% |
| Minor storm | 25% | 20% | 20% |
| Major-severe storm | 30% | 20% | 20% |
All times in UTC
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Space weather facts
| Last X-flare | 2026/06/03 | X1.0 |
| Last M-flare | 2026/06/21 | M6.9 |
| Last geomagnetic storm | 2026/06/11 | Kp5 (G1) |
| Spotless days | |
|---|---|
| Last 365 days | 3 days |
| 2026 | 3 days (2%) |
| Last spotless day | 2026/02/24 |
| Monthly mean Sunspot Number | |
|---|---|
| May 2026 | 101.4 +22.1 |
| June 2026 | 97.9 -3.5 |
| Last 30 days | 107 +10.2 |
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