Viewing archive of Thursday, 4 December 2025
Solar activity report
Report of Solar-Geophysical Activity 2025 Dec 04 2200 UTCPrepared by the NOAA © SWPC and processed by SpaceWeatherLive.com
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 338 Issued at 2200Z on 04 Dec 2025IA. Analysis of Solar Active Regions and Activity from 03-2100Z to 04-2100Z Solar activity has been at high levels for the past 24 hours.
There are currently 7 numbered sunspot regions on the disk.
IB. Solar Activity Forecast
Solar activity is expected to be moderate
with a chance for X-class flares on days one, two, and three (05 Dec, 06
Dec, 07 Dec).
IIA. Geophysical Activity Summary 03-2100Z to 04-2100Z
The geomagnetic
field has been at active to minor storm levels for the past 24 hours.
Solar wind speed reached a peak of 771 km/s at 04/1112Z. Total IMF
reached 22 nT at 03/2231Z. The maximum southward component of Bz reached
-13 nT at 04/0226Z. Electrons greater than 2 MeV at geosynchronous
orbit reached a peak level of 446 pfu.
IIB. Geophysical Activity Forecast
The geomagnetic field is expected
to be at unsettled to active levels on day one (05 Dec), quiet to active
levels on day two (06 Dec) and quiet to minor storm levels on day three
(07 Dec). Protons have a slight chance of crossing threshold on days
one, two, and three (05 Dec, 06 Dec, 07 Dec).
III. Event Probabilities 05 Dec to 07 Dec
| Class M | 75% | 75% | 75% |
| Class X | 25% | 25% | 25% |
| Proton | 15% | 15% | 15% |
| PCAF | green | ||
IV. Penticton 10.7 cm Flux
Observed 04 Dec 220 Predicted 05 Dec-07 Dec 220/220/215 90 Day Mean 04 Dec 146
V. Geomagnetic A Indices
Observed Afr/Ap 03 Dec 020/033 Estimated Afr/Ap 04 Dec 022/034 Predicted Afr/Ap 05 Dec-07 Dec 015/020-010/012-012/018
VI. Geomagnetic Activity Probabilities 05 Dec to 07 Dec
| A. Middle Latitudes | |||
|---|---|---|---|
| Active | 35% | 30% | 40% |
| Minor storm | 20% | 15% | 25% |
| Major-severe storm | 05% | 01% | 05% |
| B. High Latitudes | |||
|---|---|---|---|
| Active | 10% | 15% | 10% |
| Minor storm | 30% | 30% | 20% |
| Major-severe storm | 55% | 45% | 65% |
All times in UTC
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Space weather facts
| Last X-flare | 2025/12/01 | X1.9 |
| Last M-flare | 2025/12/04 | M6.0 |
| Last geomagnetic storm | 2025/12/04 | Kp5 (G1) |
| Spotless days | |
|---|---|
| Last spotless day | 2022/06/08 |
| Monthly mean Sunspot Number | |
|---|---|
| October 2025 | 114.6 -15.2 |
| December 2025 | 186 +71.4 |
| Last 30 days | 106.3 +12.6 |