Space Weather Observations, Alerts, and Forecast
3-day Solar-Geophysical Forecast
Product: 3-Day Forecast
- Issued: 2026 Oct 29 1230 UTC
Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center.
Geomagnetic Activity Observation and Forecast
The greatest observed 3 hr Kp over the past 24 hours was 2 (below NOAA Scale levels). The greatest expected 3 hr Kp for Oct 29-Oct 31 2026 is 5.00 (NOAA Scale G1).
| Oct 29 | Oct 30 | Oct 31 | |
|---|---|---|---|
| 00-03UT | 1.67 | 2.00 | 5.00 (G1) |
| 03-06UT | 2.33 | 1.67 | 4.67 (G1) |
| 06-09UT | 1.67 | 1.67 | 4.33 |
| 09-12UT | 1.33 | 1.00 | 4.00 |
| 12-15UT | 1.33 | 1.33 | 3.00 |
| 15-18UT | 1.33 | 3.00 | 3.00 |
| 18-21UT | 1.67 | 3.33 | 3.67 |
| 21-00UT | 2.33 | 4.33 | 4.00 |
Rationale: G1 (Minor) or greater geomagnetic storms are expected on 31 Oct due to the anticipated arrival of a recurrent positive polarity coronal hole high speed stream.
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.
| Oct 29 | Oct 30 | Oct 31 | |
|---|---|---|---|
| S1 or greater | 1% | 1% | 1% |
Rationale: No S1 (Minor) or greater solar radiation storms are expected through 31 Oct.
Radio Blackout Activity and Forecast
No radio blackouts were observed over the past 24 hours.
| Oct 29 | Oct 30 | Oct 31 | |
|---|---|---|---|
| R1-R2 | 1% | 1% | 1% |
| R3 or greater | 1% | 1% | 1% |
Rationale: No R1 (Minor) or greater radio blackouts are expected through 31 Oct.
Real Time Images of the Sun
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
Solar Cycle
The Solar Cycle is observed by counting the frequency and placement of sunspots visible on the Sun.
The forecast comes from the Solar Cycle Prediction Panel representing NOAA, NASA and the International Space Environmental Services (ISES).
The Prediction Panel's forecast called for Cycle 25 to reach a maximum sunspot number of around 115, expected around mid-2025.
Auroral Activity Extrapolated from NOAA POES
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.
Radio Communications Impact
D-Region Absorption
The D-Region Absorption Product addresses the operational impact of the solar X-ray flux and SEP events on HF radio communication. Long-range communications using high frequency (HF) radio waves (3 - 30 MHz) depend on reflection of the signals in the ionosphere. Radio waves are typically reflected near the peak of the F2 layer (~300 km altitude), but along the path to the F2 peak and back the radio wave signal suffers attenuation due to absorption by the intervening ionosphere. The D-Region Absorption Prediction model is used as guidance to understand the HF radio degradation and blackouts this can cause.
VHF and HF Band Conditions
Space weather impacts radio communication in a number of ways. At frequencies in the 1 to 30 mega Hertz range (known as “High Frequency” or HF radio), the changes in ionospheric density and structure modify the transmission path and even block transmission of HF radio signals completely. These frequencies are used by amateur (ham) radio operators and many industries such as commercial airlines. They are also used by a number of government agencies such as the Federal Emergency Management Agency and the Department of Defense.
There are several types of space weather that can impact HF radio communication. In a typical sequence of space weather storms, the first impacts are felt during the solar flare itself. The solar x-rays from the sun penetrate to the bottom of the ionosphere (to around 80 km). There the x-ray photons ionize the atmosphere and create an enhancement of the D layer of the ionosphere. This enhanced D-layer acts both as a reflector of radio waves at some frequencies and an absorber of waves at other frequencies. The Radio Blackout associated with solar flares occurs on the dayside region of Earth and is most intense when the sun is directly overhead.
Another type of space weather, the Radiation Storm caused by energetic solar protons, can also disrupt HF radio communication. The protons are guided by Earth’s magnetic field such that they collide with the upper atmosphere near the north and south poles. The fast-moving protons have an effect similar to the x-ray photons and create an enhanced D-Layer thus blocking HF radio communication at high latitudes. During auroral displays, the precipitating electrons can enhance other layers of the ionosphere and have similar disrupting and blocking effects on radio communication. This occurs mostly on the night side of the polar regions of Earth where the aurora is most intense and most frequent.
Space Weather images and data courtesy of NOAA/NWS SWPC, Mauna Loa Solar Observatory, SOHO (ESA & NASA) and hamqsl.com — see Credits for full details.
Space Weather links:
3-Day Forecast of Solar and Geophysical Activity
Space Weather Overview
LASCO Coronagraph
Real-Time Solar Wind
Space Weather Advisory Outlooks
Space Weather Forecast Disussions
Space Weather Alerts, Watches and Warnings
Solar and Heliospheric Observatory (SOHO)
The Very Latest SOHO Images