Weekly Propagation Forecast Bulletins

 Product: Weekly Highlights and Forecasts

:Issued: 2026 Sep 21 0317 UTC

# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center

# Product description and SWPC web contact www.swpc.noaa.gov/content/subscription-services

#

#                Weekly Highlights and Forecasts

#

Highlights of Solar and Geomagnetic Activity 14 - 20 September 2026

Solar activity was at very low levels on 14-18 Sep and increased to

low levels on 19-20 Sep. Region 4535 (N12, L=353, class/area Hrx/020

on 20 Sep) produced a C1.1 flare at 20/0518 UTC, while Region 4534

(N11, L=074, class/area Dro/030 on 20 Sep) produced a C3.7/1f flare

at 20/2234 UTC, the largest of the period. No Earth-directed CMEs

were detected during the highlight period. 

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit was at

high levels on 14 Sep when a maximum flux of 4,650 pfu was observed

at 14/1315 UTC. Low to moderate levels were observed on 15-20 Sep. 

Geomagnetic field activity reached unsettled levels on 14-17 Sep,

with isolated active levels observed on 14 and 16 Sep. Unsettled to

active levels were observed on 14 Sep due to a southern hemisphere

filament eruption coupled with a SSBC. Unsettled levels were

observed on 15-17 Sep, with an isolated active period early on 16

Sep, all due to negative polarity CH HSS effects. Quiet to isolated

unsettled levels were observed on 18-20 Sep. 

Forecast of Solar and Geomagnetic Activity 21 September - 17 October 2026

Solar activity is expected to be <span style="color: rgb(0, 0, 0);

white-space: pre-wrap;">at low levels, with a slight chance

</span><span style="color: rgb(0, 0, 0); white-space: pre-wrap;">for

moderate to high levels throughout the forecast period. </span> 

<span style="color: rgb(0, 0, 0); white-space: pre-wrap;">No proton

events are expected at geosynchronous orbit.</span> 

The greater than 2 MeV electron flux at geosynchronous orbit is

expected to be at high levels on 26-30 Sep, 01-03 Oct, and 05-11

Oct. Low to moderate levels are expected on 21-25 Sep, 04 Oct, and

12-17 Oct. 

Geomagnetic field activity is expected to <span style="color: rgb(0,

0, 0); white-space: pre-wrap;">reach active to G1 </span><span

style="color: rgb(0, 0, 0); white-space: pre-wrap;">storm levels on

24-25 Sep due to positive polarity CH HSS effects. Unsettled to

active levels are expected on 26-27 Sep and 04-08 Oct due to

positive polarity CH HSS effects. Quiet to unsettled levels are

expected on 11-14 Oct due to negative polarity CH HSS effects.

Largely quiet levels are anticipated for all remaining dates in the

forecast period.</span> 

Product: 27-day Space Weather Outlook Table 27DO.txt

:Issued: 2026 Sep 21 0317 UTC

# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center

# Product description and SWPC web contact www.swpc.noaa.gov/content/subscription-services

#

#      27-day Space Weather Outlook Table

#                Issued 2026-09-21

#

#   UTC      Radio Flux   Planetary   Largest

#  Date       10.7 cm      A Index    Kp Index

2026 Sep 21     105           5          2

2026 Sep 22     105           5          2

2026 Sep 23     100           5          2

2026 Sep 24     100          20          4

2026 Sep 25     105          18          5

2026 Sep 26     105          12          3

2026 Sep 27     100           8          3

2026 Sep 28     105           5          2

2026 Sep 29     110           5          2

2026 Sep 30     115           5          2

2026 Oct 01     115           5          2

2026 Oct 02     110           5          2

2026 Oct 03     105           5          2

2026 Oct 04     110          12          3

2026 Oct 05     110          15          4

2026 Oct 06     115          12          4

2026 Oct 07     115          10          3

2026 Oct 08     110           8          3

2026 Oct 09     105           5          2

2026 Oct 10     110           5          2

2026 Oct 11     100           9          3

2026 Oct 12      97           8          3

2026 Oct 13      96           8          3

2026 Oct 14      95           8          3

2026 Oct 15     100           5          2

2026 Oct 16     105           5          2

2026 Oct 17     100           5          2

(NOAA)

Weekly Propagation Forecast Bulletins

Product: Weekly Highlights and Forecasts
:Issued: 2018 Sep 10 0413 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC web contact www.swpc.noaa.gov/weekly.html
#
#                Weekly Highlights and Forecasts
#
Highlights of Solar and Geomagnetic Activity 03 - 09 September 2018

Solar activity was at very low levels this period. Region 2721 (N10, L=286 class/area Bxo/010 on 09 Sep) emerged near center disk on 08 Sep. This small region exhibited slight growth early on 09 Sep, but was showing signs of decay as of this report and remained inactive. On 09 September, a prominence eruption was observed off the SW limb,  beginning at 09/0815 UTC in SDO/AIA 304 imagery and at 09/0824 UTC in 171 imagery. While this event appears to be directed well south and west of the Sun-Earth line, significant gaps in SOHO coronagraph imagery data made analysis nearly impossible.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit reach high levels on 03 - 08 Sep, then decreased to moderate levels on 09 Sep. A peak flux of 12,435 pfu was observed on 03/2035 UTC.

Geomagnetic field activity was at quiet to unsettled levels from 03 - 09 Sep, with an isolated period of active conditions on 05 Sep, likely due to a negative polarity coronal hole. Solar wind speeds began the period near 325 km/s, increased to over 500 km/s on 05 Sep and 07 Sep, and ended the period near 400 km/s. Total field strength averaged near 5 nT, and saw a peak of 11 nT on 07 Sep. The Bz component was variable through the period and saw a maximum southward deflection of -6 nT.

Forecast of Solar and Geomagnetic Activity 10 September - 06 October 2018

Solar activity is expected to be at low levels throughout the outlook period, with a slight chance for C-class flare activity.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is expected to be at the moderate to high levels through period. Moderate levels are expected from 10 - 12 Sep and again from 29 Sep - 06 Oct. High levels are expected from 13 - 28 Sep.

Geomagnetic field activity is expected to be at quiet to active levels on 10 Sep. Conditions are then likely reach G2 (Moderate) geomagnetic storm levels on 11 Sep due to a positive polarity coronal hole high speed stream (CH HSS). G1 (Minor) geomagnetic storm levels are also likely on 12 Sep as CH HSS effects persist. Active levels are expected on 13, 14, and 22 Sep from the influence of  the recurrent CH HSSs. Field activity is expected to be at quiet to unsettled levels throughout the remainder of the outlook period.

Product: 27-day Space Weather Outlook Table 27DO.txt
:Issued: 2018 Sep 10 0413 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC web contact www.swpc.noaa.gov/wwire.html
#
#      27-day Space Weather Outlook Table
#                Issued 2018-09-10
#
#   UTC      Radio Flux   Planetary   Largest
#  Date       10.7 cm      A Index    Kp Index
2018 Sep 10      70          12          4
2018 Sep 11      70          35          6
2018 Sep 12      70          15          5
2018 Sep 13      68          12          4
2018 Sep 14      68          12          4
2018 Sep 15      68           8          3
2018 Sep 16      68           5          2
2018 Sep 17      68          10          4
2018 Sep 18      68           8          3
2018 Sep 19      68           5          2
2018 Sep 20      68           5          2
2018 Sep 21      68           5          2
2018 Sep 22      68          12          4
2018 Sep 23      67           8          3
2018 Sep 24      67           5          2
2018 Sep 25      68           5          2
2018 Sep 26      68           5          2
2018 Sep 27      68           5          2
2018 Sep 28      68           5          2
2018 Sep 29      68           5          2
2018 Sep 30      68           5          2
2018 Oct 01      68           8          3
2018 Oct 02      68          10          4
2018 Oct 03      68           5          2
2018 Oct 04      68           5          2
2018 Oct 05      68           5          2
2018 Oct 06      68           5          2
(NOAA)

Weekly Propagation Forecast Bulletins

NOAA - 'Cranky Sun'

Product: Weekly Highlights and Forecasts

:Issued: 2017 Jul 03 0114 UTC

# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center

# Product description and SWPC web contact www.swpc.noaa.gov/weekly.html

#

#                Weekly Highlights and Forecasts

#

Highlights of Solar and Geomagnetic Activity 26 June - 02 July 2017

Solar activity was very low throughout the period. Region 2664 (N18, L=313, class/area=Dsi/100 on 27 Jun) was the most active region this week but only produced low-level B-class flare activity. A very faint CME, not associated with a flare event, was  detected in coronagraph imagery midday on 27 Jun and is believed to have arrived at Earth late on 30 Jun/early on 01 Jul, causing a solar wind disturbance. Another, larger, partial halo CME associated with a long-duration B1 flare from Region 2664 was detected in coronagraph imagery midday on 28 Jun. This event is expected to arrive at Earth

on 03 Jul.

No proton events were observed at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit reached moderate levels on 26-30 Jun with normal levels observed on 01-02 Jul.

Geomagnetic field activity reached active and G1 (Minor) geomagnetic storm levels on 02 Jul due to the influence of a transient solar wind feature believed to be the passage of the  27 Jun CME. Quiet and quiet to unsettled conditions were observed throughout the remainder of the period under a nominal solar wind regime.

Forecast of Solar and Geomagnetic Activity 03 July - 29 July 2017

Solar activity is expected to be at low levels throughout the outlook period with a slight chance for isolated C-class flare activity.

No proton events are expected at geosynchronous orbit.

The greater than 2 MeV electron flux at geosynchronous orbit is expected to reach high levels on 16-19 Jul with moderate and normal levels expected throughout the remainder of the period.

Geomagnetic field activity is likely to reach G1 (Minor) geomagnetic storm levels on 03 Jul due to the anticipated arrival of the 28 Jun CME. G1 storm conditions are likely on 13 Jul with active levels likely on 14 Jul due to the influence of a recurrent negative polarity CH HSS. Generally quiet and quiet to unsettled conditions are expected throughout the remainder of the outlook period as a nominal solar wind regime prevails.

Product: 27-day Space Weather Outlook Table 27DO.txt
:Issued: 2017 Jul 03 0114 UTC
# Prepared by the US Dept. of Commerce, NOAA, Space Weather Prediction Center
# Product description and SWPC web contact www.swpc.noaa.gov/wwire.html#
#      27-day Space Weather Outlook Table
#                Issued 2017-07-03
#
#   UTC      Radio Flux   Planetary   Largest
#  Date       10.7 cm      A Index    Kp Index
2017 Jul 03      70          19          5
2017 Jul 04      70          11          3
2017 Jul 05      70           7          2
2017 Jul 06      70           7          2
2017 Jul 07      71           5          2
2017 Jul 08      71           5          2
2017 Jul 09      71           5          2
2017 Jul 10      71           5          2
2017 Jul 11      71           5          2
2017 Jul 12      71           5          2
2017 Jul 13      71          23          5
2017 Jul 14      71          13          4
2017 Jul 15      71          11          3
2017 Jul 16      72           5          2
2017 Jul 17      72           5          2
2017 Jul 18      72           5          2
2017 Jul 19      72           5          2
2017 Jul 20      71           5          2
2017 Jul 21      71          11          3
2017 Jul 22      71          11          3
2017 Jul 23      71           5          2
2017 Jul 24      71           5          2
2017 Jul 25      71           5          2
2017 Jul 26      71           5          2
2017 Jul 27      71           5          2
2017 Jul 28      70           5          2
2017 Jul 29      70           5          2
(NOAA)