Space Weather / EMI Risk Forecast

June 16th - June 20th, 2025

Summary

Space weather conditions this week are forecast to be moderate overall, with a waning coronal hole high-speed stream causing minor geomagnetic storms (G1) early in the week and an active sunspot region sustaining a heightened solar flare risk. Expect intermittent HF radio blackouts on the sunlit side from moderate solar flares (R1–R2 level), especially through mid-week. Solar radiation storm activity should remain low (no significant proton events anticipated). High-latitude regions will likely see auroral displays and minor impacts to HF communications during brief G1 geomagnetic storm periods, particularly on June 15–16, while mid and low latitudes should experience mostly normal conditions. Overall, impacts to aviation, maritime, power grids, and satellites are expected to be minimal to moderate, with short-lived disruptions rather than prolonged outages. All times below are given in UTC (with local times noted for key regions as needed).

Risk Summary

Geomagnetic Storm Risk (G-Scale)

• Current Outlook: Minor geomagnetic storming (G1) is likely on June 15–16 due to a geoeffective coronal hole high-speed solar wind stream. NOAA’s forecast indicates planetary K-index values peaking around 5 (G1) during 15–16 June, with the greatest storm activity expected on June 16 between 18:00–00:00 UTC (which corresponds to late evening in Europe and late afternoon in North America). Auroras from these G1 storms may be visible across high latitudes and possibly into upper mid-latitudes under dark skies. By June 17, geomagnetic conditions should settle back to quiet to unsettled levels (Kp ~2–3) as the coronal hole effects wane.

• Mid/Late Week: Quiet-to-active geomagnetic conditions (G0–G1) are expected for June 17–20. No strong storms are currently forecast once the early-week disturbance passes. However, forecasters are monitoring recent solar eruptions for any potential Earth-directed coronal mass ejections (CMEs). Notably, an M8.4 flare erupted on June 15 and a weak CME may graze Earth around June 17–18, possibly sparking brief active periods (Kp 4) or at most a minor G1 storm then. Confidence in any significant CME impact is low, so no major geomagnetic storms (G2+) are expected at this time.

  

• Impacts: G1 storms can induce weak geomagnetic currents; thus high-latitude power grids may experience small fluctuations but are not expected to suffer outages. Electric utility operators in northern areas will remain alert, but G1 conditions typically only produce minor grid effects. Pipeline corrosion control systems may see brief perturbations. Satellites could encounter slight increases in drag and minor surface charging during G1 events, but no serious anomalies are anticipated. Aurora enthusiasts in northern Europe, Canada, and possibly the northern continental US (upper Midwest/New England) should watch the skies on June 15–16. (For example, during last weekend’s G2 storm watch, auroras were projected as far south as New York and Idaho – this week’s G1 activity will be weaker, keeping auroras mostly to higher latitudes.)

Solar Radiation Storm Risk (S-Scale)

• Current Outlook: The risk of a solar radiation storm remains low. Energetic proton levels near Earth have stayed at background values, and NOAA forecasts only a slight chance (~15%) of any minor radiation storm (S1) in the coming days. No S1+ events have been observed in recent days. Even with several moderate flares occurring, none have produced significant solar energetic particle (SEP) enhancements.

• Impacts: No significant solar radiation storms are expected this week, meaning minimal radiation impact to aviation and space systems. High-altitude flights and polar airline routes should not encounter elevated radiation levels from the Sun (in contrast to higher-scale S3+ events). Similarly, satellite operations (including crewed spacecraft like the ISS) will not need special mitigation for solar radiation. The chance of a polar cap absorption (PCA) event – which can black out HF comms at high latitudes for hours – is very low at this time. Overall, the radiation environment should remain benign, with cosmic rays as the primary contributor (which is normal and unaffected by short-term solar activity). Spacecraft should continue to operate in nominal radiation conditions, and any slight increase in high-energy protons (should an S1 occur) would have only minor effects (e.g. enhanced single-event upset rates or sensor noise).

Radio Blackout Risk (R-Scale)

• Current Outlook: Moderate solar flare activity is ongoing, leading to a continued elevated risk of radio blackouts on HF frequencies. Active Region 4114 on the Sun is large and magnetically complex (beta-gamma-delta), capable of strong flares. Over the past 48 hours it produced multiple M-class flares, including an M8.4 event on June 15 at 18:00 UTC (R2-Moderate blackout). NOAA forecasters estimate a 55% daily probability of R1–R2 (Minor-Moderate) flares through the week, with around a 15% chance of an R3 (Strong) or greater event. In practical terms, this means we are likely to see several minor HF radio blackouts each day on the sunlit side of Earth, and there is a slim possibility of a more severe blackout if an X-class flare occurs.

• Impacts: Minor R1–R2 blackouts cause short-lived HF communication outages on the day-lit half of Earth, typically lasting minutes up to an hour at most. Expect sporadic HF signal loss during peak flare times (most flares this week have been in the M1–M5 range, causing fadeouts of several minutes on June 14–15). These will primarily affect aviation HF links, maritime HF, and amateur radio communications. Navigation systems that use sub-HF frequencies (like Loran-C or some VLF aircraft navigation aids) could see brief signal phase shifts during strong flares (R3+), but GPS/GNSS signals (at ~1.2–1.5 GHz) are largely unaffected by flare X-rays and instead are more impacted by ionospheric disturbances from geomagnetic storms. The most at-risk communications are HF radio nets – e.g. transoceanic flight HF radio, marine HF, and military HF circuits – on the dayside during a flare. Users may notice sudden drops in signal strength and increased absorption (especially at lower HF frequencies) during these blackout intervals. Fortunately, these flares are isolated events: once the X-ray flux subsides (typically within 10–30 minutes), the ionosphere recovers and HF communications return to normal. No long-duration R4–R5 blackouts are expected. In summary, plan for occasional HF outages in the daytime this week, but they should be intermittent and manageable with alternate comm methods (satellite phones, higher frequencies, or waiting out the blackout).

Radio Communication Impacts

HF (High Frequency, 3–30 MHz)

High-frequency radio communications will experience the most noticeable space-weather effects this week. The good news is that HF conditions are improving compared to the past weekend’s storm. During the G1 geomagnetic disturbances on June 14–15, HF propagation at mid-to-high latitudes was significantly degraded (reports indicated “poor” HF conditions in high latitudes on June 14 with MUFs depressed by 30–50% in some regions). As we move into June 16–17, the ionospheric disturbances should abate, allowing HF frequencies to return closer to normal propagation levels. By June 16, daytime MUFs (maximum usable frequencies) are expected to recover to near seasonal averages at mid-latitudes, and by June 17 conditions should be “normal” for most HF paths aside from minor perturbations at polar/auroral latitudes.

However, HF users should still prepare for short-term disruptions. Solar flares remain a threat: any moderate flare (R1–R2) will cause a D-layer absorption spike on the sunlit side of Earth, wiping out HF signals (especially below ~20 MHz) for a brief period. We saw this on June 14 at 23:01 UTC, when an M6.8 flare caused a ~20-minute HF blackout over the Pacific and North America. Expect similar “shortwave fadeouts” to occur sporadically this week. These will manifest as sudden loss of HF communications on daylight circuits, often observed as a dropout of signals on lower frequencies (5–15 MHz) and severe degradation up to ~30 MHz for the duration of the flare. Pilots and mariners operating HF radios should remain aware of these events – for critical messages, having a backup (such as SATCOM or VHF if in range) is prudent during daylight hours. The NOAA D-RAP model will indicate areas of strongest D-region absorption during flares (often centered on the sub-solar point). This week, any R2+ flare could cause localized HF outages for 10–30 minutes on the dayside. Regions around the equator at local noon are most affected due to higher solar angles.

Aside from flares, geomagnetic activity can also impact HF, mainly at high latitudes. During the anticipated G1 storms on June 15–16, HF signals traversing polar and auroral paths may suffer increased absorption and phase instability (auroral zone absorption). Polar routes (e.g. flights from North America to Asia over the pole) could encounter degraded HF comms and some circuits may favor lower frequencies at night or higher frequencies during the day to cope with ionospheric changes. Fortunately, since only minor storms are expected, complete HF communication blackouts in polar regions are unlikely (those typically accompany stronger proton events or G3+ storms). Nonetheless, pilots on polar flights on June 15–16 might experience patchy HF reception and should stay in contact via alternative means if available when transiting high latitudes.

Summary for HF: After a rocky start to the week, HF propagation will gradually return to normal by June 17–18. Expect fair to good conditions on most HF bands mid-week onward, with daytime MUFs in the 18–25 MHz range at mid-latitudes (supporting 14 MHz and 18 MHz long-distance contacts, for example) and night-time MUFs around 5–8 MHz on longer paths. The main caveat is the chance of sudden flare-induced outages, so users should not be alarmed by brief signal loss during daylight – these are transient. Also, during any auroral activity, HF signals on polar routes might be attenuated; rerouting through lower latitudes or using a frequency one band lower than usual can mitigate issues. Maritime HF networks and international shortwave broadcasters should schedule critical transmissions for periods outside any known disturbance windows (e.g. avoid frequencies below 10 MHz in the immediate aftermath of a flare, when absorption is strongest). Overall, we anticipate usable HF communications on all major routes for the majority of the week, with only short-lived disruptions.

VHF (Very High Frequency, 30–300 MHz)

Line-of-sight VHF communications (such as air-band VHF at ~118 MHz, VHF marine band, and land mobile radio) are generally resilient to solar activity, and this week is no exception. Most VHF users will not notice significant effects from the geomagnetic or solar flare activity. Even during strong flares, the ionospheric disturbances that affect HF do not substantially impact VHF frequencies – the shorter wavelengths pass through the D-layer with far less absorption. Thus, aircraft VHF voice comms and navigation beacons (e.g. VOR/DME) will continue to operate normally through solar flares and minor storms. Likewise, public safety and commercial VHF systems on the ground will see no direct effect from solar flares or geomagnetic activity.

One area where VHF can be influenced is in certain auroral propagation modes and satellite communications. During a geomagnetic storm, the auroral oval gets energized and can act as a reflector for VHF signals. This is of interest mainly to amateur radio operators in high latitudes – for example, 50 MHz and 144 MHz signals can sometimes bounce off aurora (known as auroral backscatter), enabling unusual beyond-line-of-sight contacts. If G1 storming occurs on June 15–16, hams in the northern US, Canada, and northern Europe might attempt 50 MHz auroral contacts in the evenings. This is a niche propagation mode and does not disrupt VHF communications, but rather provides an alternate path (often with fluttery, distorted signals). Professional communications should not be affected – for instance, civil aviation VHF does not rely on ionospheric reflection, and any aurora-related effects would be limited to slightly increased background noise in extreme cases.

Another potential impact is on VHF satellite links (for example, some low-Earth-orbit weather satellites and amateur cubesats downlink around 137 MHz or 145 MHz). During intense geomagnetic activity, ionospheric irregularities can cause scintillation (rapid signal fading) even at VHF, particularly near the auroral zones and equatorial anomaly regions. This week’s mild storms may induce very slight scintillation at high latitudes. However, given the expected G1 intensity, any scintillation on VHF will be minimal – likely below the threshold of concern for most satellite operators. VHF GNSS signals (like those used by older Loran systems or experimental beacons) could also see tiny phase shifts, but again, nothing operationally significant is anticipated for VHF.

Summary for VHF: Little to no impact. Communications in the VHF band will remain clear and reliable. Users might not even realize a geomagnetic storm is happening except for the appearance of auroras on the horizon. There are no expected VHF outages or degradations. Even in polar regions, VHF voice comm (used as backup on some polar flights) should stay fully functional since polar cap absorption primarily affects HF, not VHF. In short, VHF communications (30–300 MHz) will be nominal throughout the week. Enjoy the static-free channels – any static you do hear is more likely an artifact of local interference or tropospheric conditions than space weather this week.

UHF (Ultra High Frequency, 300 MHz and above)

Ultra-high-frequency systems, including L-band and S-band communications (used by GPS/GNSS, satellite phones, satellite TV, etc.), are also expected to perform normally for most of this week. UHF signals are even less susceptible to absorption by the ionosphere than VHF, so solar flares do not directly black out UHF links. The primary space weather concern for UHF and higher is ionospheric scintillation and satellite hardware effects from energetic particles – neither of which should be severe under this week’s conditions.

For GNSS/GPS users: No significant solar radio bursts or ionospheric disturbances are forecast to degrade GPS accuracy. During the minor geomagnetic storms (if Kp reaches 5), there could be small increases in GPS positioning error (on the order of a few meters) at high latitudes or during nighttime hours in equatorial regions, due to irregularities in total electron content. However, these effects will be minor – typical GPS devices and aviation-grade receivers will continue to meet required accuracy. WAAS and other augmentation systems might flag minor integrity alerts if ionospheric delay models sense unusual gradients, but given the G1-level activity, we do not anticipate loss of GPS service. In past G1–G2 events, some receivers in polar areas have reported a slight increase in cycle slips or need for reacquisition, but again, this is rare and quickly corrected.

For satellite communications (Satcom): Frequencies like Iridium (~1.6 GHz), Inmarsat (L-band), and Starlink (Ku/Ka band) will see no outage related to the solar flares or minor radiation environment. The only caution is that during intense auroral activity, there can be elevated noise and scintillation on trans-ionospheric links. This means a Satcom voice call at polar latitudes might experience a bit of fading or a dropped frame if the signal path intersects a turbulent auroral region. Given the mild storms forecast, any such scintillation will be very limited. The polar satellite phone networks (Iridium) have robust link margins and are designed to handle occasional fades, so no service disruption is expected. Likewise, UHF military satellite channels and C-band commercial links won’t be significantly affected by the anticipated conditions.

For radar and UHF sensors: Space weather can sometimes induce false returns on OTH (over-the-horizon) radars via ionospheric effects, but those operate in HF. Ground-based UHF weather or air-defense radars will not see any direct interference from solar activity this week. One consideration: the Sun itself is currently quite active in radio emissions. If you are pointing a satellite dish or radio telescope near the Sun, there could be bursts of solar radio noise coincident with flares – primarily affecting L-band and S-band. This is only relevant for certain specialist applications (e.g. radio astronomy) and does not impact communications services.

Summary for UHF: Nominal conditions expected. High-frequency satellite links (UHF/SHF/EHF) will remain reliable. GPS users might observe normal accuracy (~<5 m CEP) with perhaps a slight increase in PDOP during geomagnetic disturbances, but well within normal bounds. No mitigation is needed for UHF communications from space weather this week – standard operating procedures suffice.

Region-Specific Outlooks

High Latitude Regions (Arctic/Antarctic Circles and ~50°–90° geomagnetic latitude)

High latitudes will feel the brunt of this week’s minor space weather. Aurora watchers in these regions are in luck: the coronal hole stream is expected to produce auroral displays on June 15–16. Observers in northern Europe (Scandinavia, Scotland), Iceland, Greenland, Canada, and Alaska should watch for Northern Lights (aurora borealis), especially under clear dark skies on the night of June 15 into 16. Aurora visibility could extend into the northern tier of the United States and southern Canada if geomagnetic activity reaches the upper G1/lower G2 range. (Recall that during a moderate G2 storm last weekend, auroras were projected as far south as New York – roughly geomagnetic latitude ~50°. This week’s activity is slightly weaker, so auroras will likely be confined to higher latitudes such as the northern Great Lakes, Canadian Prairies, and perhaps Maine/NH in the US.) In the Southern Hemisphere, southern New Zealand and Tasmania have a shot at aurora australis on their nights of June 15 and 16 as well.

For aviation and communications in high latitudes: Expect minor HF radio disruptions during the G1 storm intervals. Polar flight routes (e.g. Asia-to-North America over the pole) on June 15/16 may encounter disturbed ionospheric conditions, requiring pilots to work closely with ATC on HF frequencies – there could be moments of fading or the need to repeat messages. Fortunately, because no solar radiation storm is occurring, we do not anticipate a complete HF blackout on polar routes (those typically happen during strong proton events). Thus, polar flights should be able to maintain HF comms, albeit with possible degradation (if HF becomes unreliable, some airlines can drop to SATCOM as needed – satellite comm should be unaffected as discussed). Magnetic compass deviations can occur in strong geomagnetic storms; during G1 events the effect is very small (milliradian level) and not significant for navigation, but it’s noted for completeness.

Infrastructure at high latitudes, like power grids in northern Europe, Canada, and Russia, might see very low-level geomagnetically induced currents (GICs) during G1 storm peaks. These currents are orders of magnitude lower than what caused issues in past extreme storms. High-latitude grid operators (e.g. in Scandinavia or Finland) often have procedures for G1–G2 storms – typically increased monitoring. This week’s G1 activity is not expected to cause any outages or equipment damage, just slight voltage fluctuations at most. The same holds for pipelines – negligible corrosion effects beyond normal.

High-frequency communications for scientific bases in the Arctic/Antarctic could be a bit noisy on June 15–16. For example, McMurdo Station (Antarctica) relies on HF; they may observe some absorption (the auroral oval in the south will likely expand north of McMurdo, so perhaps less impact there). In contrast, stations under the auroral oval (e.g. northern Alaska, Svalbard) will notice more HF signal absorption and flutter.

One positive impact: High-latitude radio propagation might improve after the storms. Often, after a coronal hole stream passes, the polar ionosphere stabilizes and HF conditions become very good. By June 18–20, expect excellent HF propagation on polar paths, with increased MUFs due to seasonal effects and a quieter geomagnetic field.

Summary (High Latitudes): Periods of G1 storming on June 15–16 will bring beautiful auroras and minor communications impacts. No serious technological problems are anticipated – just plan for a bit of HF unreliability and enjoy the light show if you’re far north (or south). By mid-week, conditions calm down, and high latitudes return to normal winter ionospheric behavior.

Middle Latitude Regions (approx. 20°–50° geomagnetic)

Middle latitude locations will have a relatively calm week in terms of space weather. Geomagnetic activity here will be felt only in a limited way. The early-week G1 storms might push the auroral oval slightly equatorward into the very northern part of this zone, but for the most part mid-latitudes will remain geomagnetically quiet outside of those brief episodes. For example, cities like New York, London, Paris, Berlin, Beijing, Tokyo fall in this category – they might see a faint aurora low on the northern horizon on June 15 or 16 if the storm peaks at local midnight and skies are clear, but it is not guaranteed. Any auroral glow would be much weaker than what high latitudes see. By June 17–20, mid-latitude magnetic fields are expected to be unsettled to quiet, with Kp ~2–3.

HF communications in mid-latitudes will be largely stable. After the minor disturbances of the 14th–15th, the ionosphere over mid-latitude paths recovers quickly. International air routes that stay at mid-latitudes (e.g. U.S. to Europe across the Atlantic at ~45–55°N) may have had some HF degradation on the 14th, but for the week of 16–20 June we anticipate good HF propagation. Daytime MUFs should climb into the 20–25 MHz range by late week with increasing solar EUV (the sun is still very active, F10.7 cm flux ~150+ sfu supporting strong ionization). Mid-latitude operators can use upper-HF bands (20 m, 17 m, 15 m amateur bands, for instance) for long-haul comm during the day, and lower bands (40 m, 80 m) at night with success. The only times mid-latitude HF circuits will falter is during the solar flares. When an R2 blackout hits, even mid-latitude paths on the dayside will lose HF for a short time. For example, a flare around noon UTC will blackout Europe–Atlantic routes (morning local time) for ~15 minutes. Users should simply wait it out or try higher frequencies if available (sometimes frequencies above about 20–30 MHz can remain partially usable during smaller flares).

Navigation systems and airlines in mid-latitudes: No radiation storm issues, so flight crew and passengers at high altitudes have nothing unusual to worry about. Standard cosmic ray exposure at 35,000 ft is unchanged (space weather adds nothing significant this week). Some airlines have policies to avoid polar routes during S3+ radiation events, but those are not applicable now.

For the general public in mid-latitudes, space weather won’t be noticeable except possibly through news of the auroras further north. Power systems and consumer electronics in these regions have no direct vulnerability to the mild geomagnetic fluctuations expected – the induced currents at these latitudes will be extremely small. One could perhaps see minor GPS accuracy variations if using high-precision modes (like RTK) during a geomagnetic fluctuation, but typical smartphone GPS or car navigation will still pinpoint you just fine (errors well under 5–10 m as usual).

Mid-latitude astronomers or night-sky photographers might want to check the northern sky on June 15/16 in case of a slight auroral glow. But note, we are near the June solstice – nights are very short in the northern mid-latitudes, which further reduces aurora visibility. (As NOAA noted in the G2 watch last week, extended daylight this time of year makes aurora spotting challenging even if the storm is strong.)

Summary (Mid-Latitudes): Quiet conditions dominate. Communications and navigation systems will operate normally, aside from brief HF hiccups during flares. No special precautions are needed for mid-latitude infrastructure. It’s essentially a normal week – with the Sun’s outbursts mostly a concern for radio operators and not much else for the average person in these regions.

Low Latitude & Equatorial Regions

Equatorial and low-latitude areas (within ~±20° of the magnetic equator) will see minimal direct impacts from this week’s space weather. Typically, low latitudes are shielded from geomagnetic storm effects by Earth’s magnetic field geometry. The G1 storms early in the week will mainly manifest at higher latitudes, so equatorial magnetometers might only register a tiny disturbance (Dst and SYM-H indices might dip slightly, indicating a modest ring current enhancement, but that’s a global effect and too small this week to cause issues).

One phenomenon to watch at low latitudes is ionospheric scintillation after sunset, especially in the equinox and solstice seasons when spread-F irregularities occur. During strong geomagnetic storms, equatorial scintillation (plasma bubbles) can intensify and interfere with GNSS signals. But with only a minor storm or two, we expect normal equatorial ionospheric behavior. There could be some post-sunset sporadic E or spread-F as usual for June, but that’s part of the climatological pattern, not driven by our current space weather in a significant way.

HF radio near the equator will be largely unaffected except by the same flare-related blackouts everyone experiences. In fact, low latitudes often benefit from increased solar activity – the HF MUFs are higher, allowing stronger daytime HF propagation on upper bands. This week, regions like Southeast Asia, Central Africa, and northern South America will likely enjoy robust HF conditions (MUFs well into 30 MHz) outside of flare times. No geomagnetic absorption issues will trouble equatorial HF paths because the auroral zones are far from the magnetic equator during these minor events.

GNSS/GPS in low latitudes: We anticipate normal accuracy and availability. Only in the unlikely event of an unforecast strong geomagnetic impulse (say from an unexpected CME) would there be a risk of enhanced equatorial scintillation that could momentarily degrade GPS. As of now, no such CME is expected. The equatorial anomaly will strengthen by day and subside by night as usual, and any variations caused by the small storm will be subtle. High-precision GPS users (surveyors, etc.) might note minor ionospheric correction variations, but nothing outside normal error budgets.

Satellite communications in tropical regions (which rely on GEO satellites for internet, TV, etc.) will not see any interference attributable to space weather this week. (Rain and local weather will remain the dominating factor for signal quality, not solar activity.)

For aviation at low latitudes, there are no space weather considerations of note. Flights in these regions don’t reach high magnetic latitudes, so they avoid polar cap issues entirely. They also often use VHF or SATCOM rather than HF for comms, meaning even the flare blackouts might not directly affect them if they’re not on HF.

Summary (Low Latitudes): Essentially no disruptions from space weather. Enjoy the stable conditions – skywave HF comm will be good, and your GPS, radio, and power systems will behave normally. If not for the global news of solar flares, equatorial residents would not notice anything unusual occurring 150 million kilometers away on the Sun.

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