Space Weather Observations, Alerts, and Forecast

3-day Solar-Geophysical Forecast

:Product: 3-Day Forecast
:Issued: 2026 Sep 15 1230 UTC
# Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center
#
A. NOAA Geomagnetic Activity Observation and Forecast

The greatest observed 3 hr Kp over the past 24 hours was 4 (below NOAA
Scale levels).
The greatest expected 3 hr Kp for Sep 15-Sep 17 2026 is 4.67 (NOAA Scale
G1).

NOAA Kp index breakdown Sep 15-Sep 17 2026

             Sep 15       Sep 16       Sep 17
00-03UT       3.00         3.67         3.67     
03-06UT       2.33         3.33         3.00     
06-09UT       0.33         3.00         2.00     
09-12UT       0.67         2.67         2.67     
12-15UT       3.00         3.00         2.67     
15-18UT       3.00         3.33         2.67     
18-21UT       3.00         3.67         2.00     
21-00UT       4.67 (G1)    4.67 (G1)    2.67     

Rationale: Active to G1 (Minor) geomagnetic storming is likely on 15 and
16 Sep, with a chance for G1 conditions persisting on 17 Sep, due to
combined negative polarity CH HSS and CME influences.

B. NOAA Solar Radiation Activity Observation and Forecast

Solar radiation, as observed by NOAA GOES-18 over the past 24 hours, was
below S-scale storm level thresholds.

Solar Radiation Storm Forecast for Sep 15-Sep 17 2026

              Sep 15  Sep 16  Sep 17
S1 or greater   20%     10%      1%

Rationale: No S1 (Minor) or greater solar radiation storms are expected.
No significant active region activity favorable for radiation storm
production is forecast.

C. NOAA Radio Blackout Activity and Forecast

No radio blackouts were observed over the past 24 hours.

Radio Blackout Forecast for Sep 15-Sep 17 2026

              Sep 15        Sep 16        Sep 17
R1-R2           10%           10%           10%
R3 or greater    1%            1%            1%

Rationale: There is a slight chance for R1-R2 (Minor-Moderate) radio
blackouts on 15-17 Sep period.

Real Time Images of the Sun

SOHO EIT 304

SOHO EIT 284

The sun is constantly monitored for sun spots and coronal mass ejections. EIT (Extreme ultraviolet Imaging Telescope) images the solar atmosphere at several wavelengths, and therefore, shows solar material at different temperatures. In the images taken at 304 Angstrom the bright material is at 60,000 to 80,000 degrees Kelvin. In those taken at 171 Angstrom, at 1 million degrees. 195 Angstrom images correspond to about 1.5 million Kelvin, 284 Angstrom to 2 million degrees. The hotter the temperature, the higher you look in the solar atmosphere.

Real Time Solar X-ray and Solar Wind

Latest LASCO Solar Corona Large Angle and Spectrometric Coronagraph (LASCO).

Real-Time Solar Wind Real-Time Solar Wind data broadcast from NASA's ACE satellite.

Space Weather Overview

The Solar Cycle is observed by counting the frequency and placement of sunspots visible on the Sun. Solar cycle 25 started in December, 2019 and is expected to complete around 2030, approximately 11 years.

Auroral Activity Extrapolated from NOAA POES

Northern Hemi Auroral Map

Southern Hemi Auroral Map

Instruments on board the NOAA Polar-orbiting Operational Environmental Satellite (POES) continually monitor the power flux carried by the protons and electrons that produce aurora in the atmosphere. SWPC has developed a technique that uses the power flux observations obtained during a single pass of the satellite over a polar region (which takes about 25 minutes) to estimate the total power deposited in an entire polar region by these auroral particles. The power input estimate is converted to an auroral activity index that ranges from 1 to 10.

VHF and HF Band Conditions

Credits: