Viewing archive of Thursday, 4 September 2025
Solar activity report
Report of Solar-Geophysical Activity 2025 Sep 04 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 247 Issued at 2200Z on 04 Sep 2025IA. Analysis of Solar Active Regions and Activity from 03-2100Z to 04-2100Z 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 likely to be moderate
with a slight chance for an X-class flare on days one and two (05 Sep,
06 Sep) and expected to be low with a chance for M-class flares on day
three (07 Sep).
IIA. Geophysical Activity Summary 03-2100Z to 04-2100Z
The geomagnetic
field has been at quiet to unsettled levels for the past 24 hours. Solar
wind speed reached a peak of 675 km/s at 04/0412Z. Total IMF reached 9
nT at 03/2327Z. The maximum southward component of Bz reached -5 nT at
04/1421Z. Electrons greater than 2 MeV at geosynchronous orbit reached
a peak level of 387 pfu.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected
to be at quiet to minor storm levels on days one and two (05 Sep, 06
Sep) and quiet to active levels on day three (07 Sep). Protons greater
than 10 Mev have a slight chance of crossing threshold on days one and
two (05 Sep, 06 Sep).
III. Event Probabilities 05 Sep to 07 Sep
| Class M | 55% | 55% | 40% |
| Class X | 10% | 10% | 05% |
| Proton | 10% | 10% | 05% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 04 Sep 172 Predicted 05 Sep-07 Sep 168/162/158 90 Day Mean 04 Sep 145
V. Geomagnetic A Indices
Observed Afr/Ap 03 Sep 008/008 Estimated Afr/Ap 04 Sep 008/010 Predicted Afr/Ap 05 Sep-07 Sep 013/018-020/025-012/015
VI. Geomagnetic Activity Probabilities 05 Sep to 07 Sep
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 40% | 35% | 40% |
| Minor storm | 30% | 30% | 15% |
| Major-severe storm | 05% | 10% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 05% | 10% | 10% |
| Minor storm | 20% | 25% | 25% |
| Major-severe storm | 65% | 60% | 55% |
All times in UTC
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Space weather facts
| Last X-flare | 2026/07/04 | X1.3 |
| Last M-flare | 2026/07/12 | M1.19 |
| Last geomagnetic storm | 2026/07/04 | Kp7+ (G3) |
| Spotless days | |
|---|---|
| Last 365 days | 3 days |
| 2026 | 3 days (2%) |
| Last spotless day | 2026/02/24 |
| Monthly mean Sunspot Number | |
|---|---|
| June 2026 | 94.4 -7.1 |
| July 2026 | 74.8 -19.6 |
| Last 30 days | 87 -20.2 |
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