Viewing archive of Tuesday, 16 September 2025
Solar activity report
Report of Solar-Geophysical Activity 2025 Sep 16 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 259 Issued at 2200Z on 16 Sep 2025IA. Analysis of Solar Active Regions and Activity from 15-2100Z to 16-2100Z Solar activity has been at low levels for the past 24 hours.
There are currently 9 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 (17 Sep, 18 Sep,
19 Sep).
IIA. Geophysical Activity Summary 15-2100Z to 16-2100Z
The geomagnetic
field has been at quiet to minor storm levels for the past 24 hours.
Solar wind speed reached a peak of 857 km/s at 16/0022Z. Total IMF
reached 6 nT at 15/2121Z. The maximum southward component of Bz reached
-4 nT at 15/2321Z. Electrons greater than 2 MeV at geosynchronous orbit
reached a peak level of 3346 pfu.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected
to be at quiet to active levels on day one (17 Sep), quiet to unsettled
levels on day two (18 Sep) and quiet levels on day three (19 Sep).
III. Event Probabilities 17 Sep to 19 Sep
| Class M | 30% | 30% | 30% |
| Class X | 01% | 01% | 01% |
| Proton | 01% | 01% | 01% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 16 Sep 135 Predicted 17 Sep-19 Sep 138/138/140 90 Day Mean 16 Sep 144
V. Geomagnetic A Indices
Observed Afr/Ap 15 Sep 034/048 Estimated Afr/Ap 16 Sep 017/022 Predicted Afr/Ap 17 Sep-19 Sep 013/015-009/010-006/005
VI. Geomagnetic Activity Probabilities 17 Sep to 19 Sep
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 35% | 20% | 10% |
| Minor storm | 15% | 05% | 01% |
| Major-severe storm | 01% | 01% | 01% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 15% | 15% | 15% |
| Minor storm | 30% | 25% | 20% |
| Major-severe storm | 50% | 30% | 20% |
All times in UTC
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Space weather facts
| Last X-flare | 2026/03/30 | X1.5 |
| Last M-flare | 2026/04/04 | M1.0 |
| Last geomagnetic storm | 2026/04/03 | Kp7- (G3) |
| Spotless days | |
|---|---|
| Last 365 days | 3 days |
| 2026 | 3 days (3%) |
| Last spotless day | 2026/02/24 |
| Monthly mean Sunspot Number | |
|---|---|
| March 2026 | 85.9 +7.7 |
| April 2026 | 128.3 +42.3 |
| Last 30 days | 97.5 +35.7 |
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