Product: Weekly Highlights and Forecasts
:Issued: 2026 May 25 0601 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
Highlights of Solar and Geomagnetic Activity 18 - 24 May 2026
Solar activity ranged from low to moderate levels. The largest flare was an M2.3 (R1-Minor) at 22/1029 UTC from Region 4436 (N18, L=333, class/area Dai/200 on 13 May). The region was also responsible for a C8.3 and C9.5 flares on 21/1814 UTC and 21/1825 UTC, respectively. This region was then responsible for the majority of the C-class activity until its rotation off the W limb on 21 May. On 23-24 May, the majority of the C-class activity occurred from Region 4446 (S13, L=141, class/area Dko/280 on 24 May). No Earth-directed CMEs were observed during the period.
No proton events were observed at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit reached high levels on 18-24 May due to CH HSS influences. The highest flux observed was 6,667 pfu at 18/1435 UTC.
Geomagnetic field activity ranged from quiet to active levels. Solar wind parameters began the period in a slow decline from 560 km/s as negative polarity CH HSS effects gradually diminished. At 19/0630 UTC, a small shock was observed increasing total field to 7-8 nT while solar wind speed increased to near 625 km/s before beginning to decline once again. This was likely the glancing effects from a CME that left the Sun on 16 May. Solar wind speed continued to decrease to nominal levels through 22 May. The geomagnetic field reacted with quiet to active levels on 19 May. Quiet to unsettled levels were observed on 18 May and 20-22 May. Quiet conditions occurred on 23-24 May.
Forecast of Solar and Geomagnetic Activity 25 May - 20 June 2026
Solar activity is expected to be at low to moderate levels (R1-R2, Minor-Moderate) on 25 May through 07 Jun with the return of old Region 4432 (N14, L=081). Mostly low levels with a chance for M-class flares is expected from 08-20 Jun.
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 25-27 May and 12-20 Jun due to CH HSS influences.
Geomagnetic field activity is expected to be at unsettled to active levels on 27-29 May, 04 Jun, 09 Jun, and 11-15 Jun due to recurrent CH HSS activity. G2 (Moderate) storm conditions are likely on 11 Jun
and G1 (Minor) storming on 12 Jun due to CIR/CH HSS onset.
Product: 27-day Space Weather Outlook Table 27DO.txt
:Issued: 2026 May 25 0601 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 2026-05-25
#
# UTC Radio Flux Planetary Largest
# Date 10.7 cm A Index Kp Index
2026 May 25 140 5 2
2026 May 26 145 8 3
2026 May 27 150 12 4
2026 May 28 140 12 4
2026 May 29 140 8 3
2026 May 30 145 5 2
2026 May 31 145 5 2
2026 Jun 01 145 5 2
2026 Jun 02 145 5 2
2026 Jun 03 150 5 2
2026 Jun 04 145 15 4
2026 Jun 05 140 5 2
2026 Jun 06 135 5 2
2026 Jun 07 135 5 2
2026 Jun 08 130 5 2
2026 Jun 09 125 12 4
2026 Jun 10 130 5 2
2026 Jun 11 130 30 6
2026 Jun 12 125 25 5
2026 Jun 13 120 12 4
2026 Jun 14 115 10 3
2026 Jun 15 115 8 3
2026 Jun 16 110 5 2
2026 Jun 17 110 5 2
2026 Jun 18 110 5 2
2026 Jun 19 115 5 2
2026 Jun 20 120 5 2
(NOAA)
